35+ Years of Freedom of Information Action

The British Bomb and the United States - Part One

President Eisenhower and Prime Minister Macmillan

President Eisenhower and Prime Minister Macmillan at the White House 25 October 1957, the day after they discussed exchanges of nuclear weapons information. From left to right: seated--Macmillan, Eisenhower, and NATO Secretary-General Paul Henri Spaak; standing—British Foreign Secretary Selwyn Lloyd and Secretary of State John Foster Dulles. Spaak visited Washington for discussions of the broader NATO response to the Soviet Sputnik challenge. (National Park Service photo 72-2481-2 in collections at the Dwight D. Eisenhower Library and Museum).

Published: May 13, 2021
Briefing Book #763

Edited by William Burr

For more information, contact:
202-994-7000 or nsarchiv@gwu.edu

Prime Minister Macmillan was determined to “stay in the nuclear club”

U.S. officials (correctly) believed British wanted independent capability to strike Soviets if Washington did not come to their aid

Dean Rusk saw danger of U.K. tending to “move in on our independence”

Washington, D.C., May 13, 2021—­British leaders were determined to become a nuclear power after World War II in part so they could have a “seat at the top table” of international negotiations, according to a 1965 State Department intelligence report published today by the nongovernmental National Security Archive.  London also wanted to be able to present its own “independent” deterrent to the Soviet Union to mitigate its reliance on U.S. forces, records show. 

Documents obtained by the Archive provide important perspective on the recent British decisions to raise the ceiling on their nuclear stockpile, a move the Biden administration has yet to comment on publicly.  The new materials explore several topics and events that underlie the secrecy-shrouded U.S.-U.K. nuclear relationship and reveal interesting attitudes toward nuclear weapons that officials kept scrupulously private.

For example, for many U.S. officials, Britain’s national nuclear program was an irritant; Washington pushed for London instead to join a multilateral force.  The documents point to a number of American motivations, including high costs and the risk of proliferation, but it was also a question of control.  “[T]he more the UK stressed its independence the more it tended to move in on our independence,” Secretary of State Dean Rusk observed.

Rusk went on to comment on the mixed advantage of being a nuclear power: “[T]he employment of nuclear weapons is not a path to freedom but a path to slavery” since the U.S. “has never had less independence than it has today in the areas affected by these weapons.”  

Today’s posting—the first of a two-part series—begins with the late 1950s when President Dwight D. Eisenhower and Prime Minister Harold Macmillan agreed to highly secret exchanges of nuclear weapons design information. It continues into the Kennedy administration and includes documents on the 1962 Skybolt crisis that led to a joint U.S.-U.K. decision to deploy Polaris re-entry vehicles on missiles carried by British submarines.  It concludes with the early stages of British discussions with Washington of a Polaris follow-on that would be less vulnerable to Soviet anti-ballistic missiles.

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The British Bomb and the United States - Part One

by William Burr

Ever since the post-World War II years, the leaders of the United Kingdom have sought nuclear weapons so they would have a “seat at the top table” of international negotiations, according to a 1965 State Department intelligence report. Yet, the British nuclear program has involved a close association with the United States. During the early 1960s, Secretary of Defense Robert McNamara wrote to President John F. Kennedy that the British have been cooperative in nuclear matters because their “foreign policy for a century has rested on the proposition that it cannot afford a fundamental split with the U.S.” With that premise in mind, London has “accepted the status of junior partner in the firm in exchange for a special relationship which they believe affords them a unique opportunity to influence U.S. policy.”

Much has changed since the 1960s, but U.S.-U.K. nuclear policy coordination continued for decades, although its current status is shrouded in secrecy. The “Integrated Review” of British defense policy, released by the British Conservative Government in March 2021, raises questions in that respect because of its plan to increase the UK’s small nuclear force. The British have kept nuclear weapons stockpile numbers low for years and declared in 2010 and at the 2015 Nonproliferation Treaty Review Conference that their force would be reduced to no more than 180 weapons by the middle 2020s. Moreover, in 2010, the British declared that operationally available warheads would not exceed 120. Pointing to a changed and more threatening global environment, however, the Boris Johnson Government has reversed that, declaring that it would raise the cap and move to a stockpile ceiling of 260. Moreover, it declared that it would put no limits on the number of Trident missiles and nuclear warheads on each of its “Dreadnaught Class” submarines, due to come into service in the 2030s. (The previous numbers were 8 missiles and 40 warheads; the new numbers would be kept secret.)

The British plan to raise stockpile numbers and the scope of the Trident deployments has been widely criticized in the arms control community as inconsistent with the NPT’s goal of reducing nuclear stockpiles and eventually eliminating them.[1] With an NPT Review Conference coming up the British move will not have a calming impact on global nonproliferation policy. It also puts a spanner in the works of the current effort by the Stockholm Initiative for a “stepping stones” approach to nuclear disarmament.

It is not yet known whether Prime Minister Johnson and the Ministry of Defense consulted with Washington before making the announcement, although it is likely that they did. While what Johnson proposes to do would have probably been satisfactory to the previous U.S. administration, the Biden White House has kept its own counsel, making no statement about the British announcement. As it is already on record as favoring moves to reduce nuclear stockpiles and lessen reliance on nuclear weapons in national policy, the current White House may see the new British policy as an unwelcome development in a world where nuclear proliferation is increasing. What this means for U.S.-UK relations is uncertain.

For decades during the Cold War and after, close Anglo-American cooperation in nuclear matters has been a matter of record. For example, since the 1950s both London and Washington have made private and highly secret pledges to consult with one another in the event of a decision to use nuclear weapons (time permitting). It is not clear whether recent presidents and prime ministers, including President Joe Biden and Prime Minister Johnson, have continued such pledges. Moreover, for decades during and after the Cold War, close US-UK nuclear military cooperation obtained, marked by exchanges of sensitive nuclear weapons information and the sale of advanced nuclear delivery systems. To this date, British ballistic missile-launching Vanguard submarines carry Trident II submarine launched ballistic missiles (SLBMs) manufactured by Lockheed-Martin in California.

To put recent developments in perspective, this posting—the first of a two-part series—explores aspects of the U.S.-U.K. special nuclear relationship. It begins with the late 1950s when President Dwight D. Eisenhower and Prime Minister Harold Macmillan agreed to highly secret exchanges of nuclear weapons design information and signed off on protocols for consultations on the launching of nuclear weapons. It includes documents on the Skybolt Affair when the Kennedy administration cancelled a bomber-launched missile that the British were counting on, but which led to a U.S.-U.K. agreement on providing Polaris SLBMs to arm British nuclear-powered submarines. The British “Resolution” submarines began entering service in the late 1960s, just as the Soviets were deploying anti-ballistic missile systems, which threatened the ability of Polaris missiles to strike Moscow and other priority targets. Part one will conclude with documents about British concerns over the ABM threat and the early stages of consultations with Washington on their developing plans for an upgraded Polaris warhead and re-entry vehicle.

Early in World War II, as Washington and London were moving towards a virtual alliance relationship, British scientists developed initial concepts for atomic explosives and played an important role in inspiring the creation of the wartime Manhattan Project and making significant contributions to the work at Los Alamos.[2] After the war, to the dismay of the British, the Atomic Energy Act prohibited the disclosure of any nuclear weapons information to foreign governments. London tried for years to restart the information sharing arrangement, but it had ample scientific and technical skills to move ahead on its own. Both Labour and Conservative Governments were determined that the United Kingdom enter the nuclear club not only for security reasons but so that Britain would be taken seriously as a world power. In October 1952, the British staged their first atomic test in the Monte Bello islands, off the northwest coast of Australia. Five years later, they were testing thermonuclear weapons. [3]

While nuclear relations were difficult after the war, Anglo-American diplomatic, financial, and military ties remained close. It was often an uneasy relationship, marked by great disparities in power, although the British played their dependent role with some skill. In terms of nuclear matters an important element of the relationship was the presence of U.S. military bases, up to 100 by the early 1990s, although they are now down to some 13 in all. By 1951, the U.S. was storing nuclear weapons at British bases and flying with the weapons in British airspace on a routine basis. The Strategic Air Command (SAC) deployed heavy bombers, first B-29s then B-47 medium-bombers at the bases. Later in the decade, the U.S. Air Force supplied Thor intermediate-range ballistic missiles to the Royal Air Force (RAF) under a dual key, U.S.-U.K. control arrangement.

Before the British began producing enough atomic weapons of their own, Washington and London devised the highly secret “Project E” program, which assigned atomic bombs to the Bomber Command if world war broke out. Information exchanges slightly loosened during the mid-1950s, with legislative changes making it possible to share data on peaceful uses of nuclear energy and some details on the use of nuclear weapons. That made it possible for the U.S. Air Force to share technical details on the bombs with the RAF. Nevertheless, data on the design and production of nuclear weapons could not be shared.[4]

By 1957, with the military-technological competition with the Soviet Union intensifying, the Eisenhower administration wanted to restore nuclear information exchanges to improve both the U.S. and the British military postures. Eisenhower wanted to be “better partners” with the British so it would be possible to “talk about nuclear weapons just as we do about rifles or bayonets.” This eventually inaugurated a close nuclear relationship that involved the sharing of sensitive weapons design information. Moreover, in 1960 Eisenhower and Macmillan agreed to arrangements allowing for the docking of U.S. Polaris submarines at bases in Scotland. The Polaris basing was tacitly linked to the provision of Skybolt missiles. With the U. S’s cancellation of Skybolt, owing to cost considerations, at the December 1962 Nassau conference, the Kennedy administration agreed to sell Polaris SLBMs to the British as a consolation prize. That arrangement would have lasting implications because it kept the United Kingdom in the “nuclear club” and sustained London’s determination to stay in the “nuclear club.”[5]




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Source: National Archives, Record Group 59, Department of State Records [hereinafter RG 59], Deputy Assistant Secretary for Politico-Military Affairs Subject File, Special Assistant for Atomic Energy Affairs, 1950-1966, box 3, 1.1.B Macmillan Visit - October 1957


With the Soviet Union’s Sputnik flight demonstrating Moscow’s advances in missile technology, the Eisenhower administration was under pressure to advance space and missile programs, but also to reassure allies about U.S. commitments to their security. British Prime Minister Harold Macmillan came to Washington for talks with Eisenhower about strengthening alliance relations. This briefing paper was prepared for the talks in which it was anticipated that Anglo-American nuclear cooperation would be discussed, that the British would call for expanding it, and that the United States could respond favorably. Among the measures that could be taken if legislation permitted it would be provision of enriched uranium for British propulsion reactors and weapons, the sharing of sensitive design information, cooperation in nuclear testing, and improved training in the use of nuclear weapons. That could save both countries from undertaking expensive and redundant R&D programs and help the British improve the “efficiency and usefulness” of their weapons stockpile. Also under consideration was the sale of highly enriched uranium (the U.S. having lower production costs) to the British for submarine reactors and weapons production.


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Source: RG 59, Deputy Assistant Secretary for Politico-Military Affairs Subject File, Special Assistant for Atomic Energy Affairs, 1950-1966, box 3, 1.1.B Macmillan Visit - October 1957


When Macmillan and his advisers travelled to Washington in Fall 1957 to meet with Eisenhower administration officials, the disastrous fire at the Windscale nuclear reactor on 10 October was just behind them. It probably colored U.S. official perspectives of the U.K. nuclear program because the British acknowledged to representatives of the Hanford (Washington) plant that it was the “first serious blow” to the invincible reputation of their atomic scientists.[6] In any event, the degree to which, or even whether, the U.S. should help the British improve their nuclear weapons was controversial in some quarters.

After Macmillan and Eisenhower met on the morning of 24 October, U.S. and British representatives prepared a joint report to Eisenhower and Macmillan on nuclear information sharing [see Document 4]. After the British representatives Edwin Plowden and Richard Powell left the meeting, the Americans discussed how far the United States should go in sharing sensitive details on nuclear weapons technology. Though President Eisenhower had called for a “full partnership”, he had reservations about the degree of information sharing. Going even further was Atomic Energy Commission Chairman Lewis Strauss who thought that the British should leave of the bombmaking business altogether (though if he explained why it is not recorded here). [7]

Sensitive information on boosting, fusion, and radiation implosion—important technical innovation underlying the H-bomb—were not to be shared. General Herbert Loper, Chairman of the Military Liaison Committee of the United States Atomic Energy Commission, argued that if that were so, there was “little point to the agreement that had just been drawn up” and that the British would be denied information that the Soviets already knew, such as the “two-stage thermonuclear weapon.” Gerard C. Smith, at the time director of policy planning at State, argued that the British would be shocked to learn that, having been told that morning that there was a “full partnership,” they would “not get anything the Russians did not already have, and perhaps less.”

The “Grapple” series of nuclear tests that the British would conduct in the South Pacific during 1957 and 1958 (with U.S. observers present) achieved success with boosted fission, radiation implosion, and two-stage thermonuclear devices, but apparently those results were not yet understood at the Atomic Energy Commission or at least by Chairman Strauss.[8]


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Source: RG 59, Deputy Assistant Secretary for Politico-Military Affairs Subject File, Special Assistant for Atomic Energy Affairs, 1950-1966, box 3, 1.1.B Macmillan Visit - October 1957


After the Macmillan-Eisenhower meeting on the morning of 24 October, Smith called Secretary of State Dulles to tell him about “important reservations” concerning the Strauss-Plowden memorandum (see Document 4). Dulles discussed the problem with Eisenhower and then Macmillan joined in the conversation. Eisenhower explained that “there were a few, about four, applications of such high secrecy [that] he did not think that these could be the subject of joint pooling unless and until we were satisfied that the Soviets themselves knew about them.” The Soviets probably knew about two of them which meant that only two had to be “restricted.” Macmillan said he understood.


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Source: RG 59, Deputy Assistant Secretary for Politico-Military Affairs Subject File, Special Assistant for Atomic Energy Affairs, 1950-1966, box 3, 1.1.B Macmillan Visit - October 1957


Starting from the premise that important “blocks” prevented the exchange of nuclear weapons information, once they had been removed, AEC Chairman Strauss et al. suggested area where information could be exchanged, including transfers and exchanges of nuclear materials, exchange of weapons information and rationalization of weapons projects, U.S. supply of weapons systems, such as tactical nuclear weapons or submarine propulsion units, and operational information on use of nuclear weapons (which could be expedited by the removal of existing restrictions). Toward those and other ends, more consultations would follow in December and the working group would report its findings.[9]


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Source: RG 59, Central Decimal Files, 1955-1959, 741.5611/6-858 (released on appeal)


Reached after a long negotiating process, this agreement on nuclear retaliation procedures stemmed from direct pressure from Prime Minister Macmillan for a detailed formal accord governing U.S. and British decisions to initiate such a launch. The agreement enshrined an understanding that had been first reached in October 1951that the use of nuclear weapons from U.S. bases in the United Kingdom would be a matter of “joint decision.” While British leaders also wanted to be consulted on U.S. decisions to use nuclear weapons generally, from the U.S. perspective that would depend on the "circumstances prevailing at the time," reflecting U.S. insistence on freedom of action.[10]

The Murphy-Dean agreement established a protocol for future consultations. If circumstances permitted a conference call between the president and the prime minister, the agreement spelled out the process of decision that would occur under two different situations: 1) strategic warning (longer-term warning of attack) and tactical warning ("short warning of imminent attack derived from positive radar or other means"). Strategic warning could permit a decision to launch a preemptive assault on Soviet nuclear forces, although whether any warning would be certain enough to allow such a grave decision has been a matter of debate for many years. In the event of tactical warning, military commanders could launch forces under "positive control" (also known as "fail safe”); thus U.S. and British bombers would fly to a "specified line" but would not pass beyond it without receiving definite instructions.

Previously excised from an earlier declassification are passages concerning the British chain of decisions as well as references to nuclear weapons of U.S. origin that had been provided secretly through “Project E.” The British decisions concern what the prime minister and the chief of the Air Staff would do in event of strategic warning or tactical warning. For example, among the decisions that the prime minister and the U.S. president would have to agree upon was whether an attack, preemptive or retaliatory, would include weapons of U.S. origin, which would be used by Thor IRBMs and the British medium bomber force. The details of the agreement would be modified over time owing to changes in U.S. delivery systems and weapons deployed in the United Kingdom and changes in targeting responsibilities.[11]


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Source: RG 59, Bureau of European Affairs, Office of British Commonwealth and Northern European Affairs, Alpha-Numeric Files Relating to the United Kingdom, 1949-1962, box 2, United Kingdom-Atomic Weapons Agreement with United Kingdom


Much of the U.S. record on the story of the Anglo-American nuclear negotiations on cooperation during 1957-1958 remains classified, but British progress in developing and testing thermonuclear weapons persuaded Washington that the “full partnership” that Eisenhower had in mind—sharing sensitive nuclear weapons design data—was possible and necessary. By the summer of 1958, Congress had amended the Atomic Energy Act so that it would be possible to share restricted data with states that had made “substantial progress” in weapons development, if the president determined that such exchanges were in the U.S. interest. With an agreement having been signed formalizing the possibility of information exchanges, British officials visited Washington for talks in late August 1958; as a result, the AEC was prepared to recommend to President Eisenhower a “favorable finding on the transmission of certain information now held by us.” This would include design information on warheads for various bombs and missiles, anti-submarine weapons, and gun shells. Moreover, according to Assistant Secretary Philip Farley, the U.S. “might well benefit from the receipt of certain information” from the British relating to those weapons along with “theoretical and design information.”[12]


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Source: DNSA; from RG 59, Office of Atlantic Political and Military Affairs, Records Relating to NATO, 1957-1964, box 1, IRBM-UK


A major U.S. nuclear deployment in the United Kingdom was the Thor IRBMs that became operational in the summer of 1960, several years after negotiations had begun in 1957. By the late summer of 1958, the missiles were arriving, but several steps had to be taken before they were anywhere near operational, as this record of a meeting of Air Force officials on both sides disclosed. The British did not have the warheads and they needed to know “who does what to what” before the missiles could be truly called operational. Among other deficiencies, the British did not have up-to-date manuals showing how to fire the missiles or even accurate information on “where the sites [presumably warhead storage] are,” or on how long the missiles “could be maintained in a pressurized state and ready to go,” much less on how to target them. According to Air Force General Roscoe Wilson, what “really worried” the British was that under national regulations they could not transport the warheads on roadways, which meant that the Thors could “hardly ever” be considered operational. That problem was eventually solved, but in the meantime the Royal Air Force tried to prevent that “bit of information” from reaching Prime Minister Macmillan.


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Source: RG 59, Bureau of European Affairs, Office of British Commonwealth and Northern European Affairs, Alpha-Numeric Files Relating to the United Kingdom, 1949-1962, box 2, U.K. Nuclear Weapons and Missiles


Reporting on the state of play concerning various weapons and warning systems, a contentious issue—whether Thor IRBMs should be deployed with nuclear warheads attached (“mated”) had apparently been resolved, although it was not clear whether the mating had occurred. A difficult problem for the British was whether to go ahead with the Blue Streak IRBM program or to abandon it in favor of the Skybolt bomber launched missile, which was undergoing development in the United States. President Eisenhower had agreed to provide Skybolt, less the nuclear warhead, as long as its development program was “successful and timely.” Therefore, Macmillan controversially cancelled Blue Streak. According to British plans, their nuclear deterrent would consist of Thor IRBM and the “V” bomber force armed with Skybolt missiles. In some quarters of the government, there was interest in acquiring Polaris missile-launching submarines, but no decisions had been made. Not known to the author of this paper was that Macmillan understood U.S. support for Skybolt as part of a deal involving British agreement to U.S. use of Holy Loch as a base for Polaris submarines [see Document 18].[13]


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Source: DNSA, from Dwight D. Eisenhower Library, Office of the Special Assistant for Science and Technology, box 12, Missiles 7/60-9/60


Only months after Eisenhower had advised Macmillan that Skybolt’s future depended on a successful development program, the missile was getting unfavorable internal reviews. According to a President’s Science Advisory Committee (PSAC) subcommittee, Skybolt duplicated other defense programs and did not “confront the enemy with a significant new defense problem.” The Hound Dog air-to-surface missile, which was already being deployed on U.S. B-52s “pose[d] a serious problem for Soviet air defense.” According to the report by a PSAC subcommittee, “serious consideration should be given to cancel Skybolt before more effort and money is expended.” While such a decision would cause “embarrassment” for the British, the “case for Skybolt for the RAF appears weak anyway.” Nevertheless, SAC supported Skybolt and would take it for granted that it would eventually be available for both its and the UK’s bombers (see Document 12).


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Source: Library of Congress, Thomas D. White Papers, box 29, Top Secret General 1959


General Pike informed Air Force Chief of Staff White that the British would be ending “Project E”, which had supported the British bomber force with U.S. nuclear weapons. Implicitly, the British would be producing enough nuclear weapons on their own to support strike missions by the “V” force. Until “Project E” concluded in March 1962, about half of the bomber force would have relied on U.S. nuclear weapons to carry out their strike missions. Such action would have required permission from the U.S. president, a significant limitation on British freedom of action in a crisis.[14]


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Source: DNSA; from NARA, Robert McNamara Papers, box 113, Reading File, December 1961


For Defense Department officials, Skybolt’s future remained murky. Noting higher costs for Skybolt, Secretary of Defense McNamara observed that “there are limits to what we should be willing to pay.” While acknowledging that Skybolt had “value” for defense suppression, McNamara saw Hound Dog and Minuteman missiles as just as valuable. Concluding that if Skybolt could be completed within cost totals making them “substantially less than Minuteman,” it would be worth supporting. Otherwise, “we should not continue.” The implications for relations with London were not discussed in this paper, but the British knew about the mixed reviews that Skybolt had been receiving from McNamara and others.


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Source: DNSA, from RG 59, Central Decimal Files, 375/12-761


During Raymond Albright’s visit to SAC headquarter, briefers cited several examples of the “special relationship,” including the role of Ballistic Missiles Early Warning System [BMEWS] sites in the UK for warning SAC and British forces of missile attacks; SAC plans to purchase Skybolt missiles, which would also be available to the Bomber Command; and bi-annual SAC and Bomber Command targeting conferences. Another example of cooperation was the computations at SAC headquarters of the trajectories that would be used for Thor IRBMs deployed in the U.K. Albright did not provide details of targeting, but by 1962 “the coordinated Anglo-American plan involved the V-bomber force and Thors in attacks against the Soviet Union on 16 cities, 44 airfields, 10 air defense control centers, and 28 IRBM sites.”[15]

Albright noted that these examples of U.K.-U.S. practical cooperation tended to undercut a White House directive from April 1961 which favored downgrading the “special relationship” in favor of greater British integration into Western Europe, the desirability of a British decision “to phase out of the nuclear deterrent business,” and the lack of a need to “prolong the life” of the British bomber force if Skybolt was “not warranted for U.S. purposes alone.”


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Source: Library of Congress, Paul H. Nitze Papers, box 221, folder 14 (copy courtesy of Matthew Jones)


On 16 June 1962, Secretary of Defense Robert McNamara gave a speech on nuclear policy at the University of Michigan; a major theme was the importance of centralized U.S. control over alliance nuclear forces and the danger of small, national nuclear forces, whose use against the cities of a major nuclear power would be “tantamount to suicide.” Moreover, the creation of new national nuclear forces “encourages the proliferation of nuclear power with all its attendant dangers.” As he put it, “limited nuclear capabilities, operating independently, are dangerous, expensive, prone to obsolescence, and lacking in credibility as a deterrent.” The statement caused heartburn in London because it appeared to ignore the close coordination between British and U.S. strategic planners. While McNamara made a clarifying comment saying that his remarks did not apply to the U.K.’s Bomber Command, British suspicions lingered that Washington wanted to force them out of their national nuclear role.

The day of the speech, a memorandum that McNamara sent to President Kennedy suggested, implicitly, that as much as the U.S. preferred that independent national nuclear forces go by the wayside, it would be unlikely to take disruptive action against the British. The paper focused on the French nuclear problem and the difficulty of reaching an understanding with President Charles De Gaulle on nuclear matters. In an interesting section of the paper, McNamara elaborated on the “clear distinction” between relations with the U.K. and with France. Unlike the French, the British have been cooperative in nuclear matters because their “foreign policy for a century has rested on the proposition that it cannot afford a fundamental split with the U.S.” With that premise in mind, London has “accepted the status of junior partner in the firm in exchange for a special relationship which they believe affords them a unique opportunity to influence U.S. policy.” Moreover, London had been “willing to live within the nuclear policy favored by the U.S.” In that context, a “harmonious” nuclear relationship had been quite profitable to the British and one which they were unlikely to give up because it would be “costly to British prestige” and disruptive to research organizations, security forces, and engineering industries.[16]


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Source: RG 59, Executive Secretariat Conference Files, 1949-1972, box 291, CF 2163 Secretary's European Trip, June 18-28, 1962 MemCons


In the shadow of McNamara’s speech, there were pressures within the State Department to follow through on the April 1961 directive to encourage the British to abandon their national nuclear weapons program. Rusk was not totally in synch with that approach, which would have required British participation in a multilateral force, but he did not have an alternative. Nevertheless, Rusk objected to any notion that British nuclear forces could be used independently of U.S. policy. In a remarkable comment to British Foreign Minister Lord Home, Rusk argued against the idea of nuclear independence, declaring that “the employment of nuclear weapons is not a path to freedom but a path to slavery. The U.S. has never had less independence than it has today in the areas affected by these weapons” because it has to be responsible to allies. “The responsibility which the possession of these weapons brings inhibits our freedom of action.”

Rusk also argued that the British emphasis on an independent nuclear force was inconsistent with U.S. interests: “the more the UK stressed its independence the more it tended to move in on our independence.” By citing the “the theoretical problem with which Khrushchev and President Kennedy would be confronted if missiles should be fired from the UK,” Rusk indicated how alarming the prospect of nuclear independence was to Washington.[17]


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Source: RG 59, Central Decimal Files, 741.5611/8-1062


In a short paper that anticipated elements of the eventual resolution of the Skybolt crisis, State Department official Robert Kranich observed that the Skybolt missile was “vulnerable and obsolete”—like the Thor IRBM—because, unless the bombers were moved out of the UK, they would have to be on “continuous airborne alert.” To resolve the problem, he suggested an offer to the British: get rid of Skybolt, start a Polaris program with missile targeting integrated into the SIOP, and commit the submarine force to an eventual “European deterrent.” If the British made the commitment, it would be permissible for them “to enjoy [a] legal fictional right of national withdrawal.” Kranich thought that the British “might accept this.” Moreover, the same offer could be made to De Gaulle, although the French were likely to reject. In any event, Kranich’s proposal would have little traction at the State Department where powerful supporters of the Multilateral Force (MLF) would have rejected any prospect of transitional British national control of a Polaris force, much less a “right of national withdrawal.”


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Source: F. K. Library, National Security Files, box 228, NATO, Weapons, Nassau Basic Documents,12/19/62-2/7/63, folder 1/2. Expurgated version published in Foreign Relations of the United States, 1961–1963, XIII, Western Europe and Canada(Washington, D.C., Government Printing Office, 1994), doc.402


Increases in Skybolt’s cost finally brought Robert McNamara to a decision to cancel the missile, telling British Ambassador Ormsby Gore in November 962 that such action was likely. While McNamara privately believed that a British Polaris program would be an acceptable way for Washington and London to continue collaboration in the nuclear weapons field, senior officials at State and Defense objected to that, and he held back that card. Seeing the missile as key to the viability of the bomber force, the cancellation came as a shock to Macmillan, who believed that he had an understanding with Eisenhower.

In December 1962, Kennedy and Macmillan had a scheduled meeting in Nassau, Bahamas, just in time to discuss Skybolt and its alternatives. To prevent the problem from turning into a crisis that could bring down Macmillan’s government and further damage U.S. credibility, Kennedy and his advisers agreed that Washington owed Macmillan a replacement for Skybolt—to sell Polaris missiles on the condition that the British assign them and the submarines to NATO or possibly to a larger multilateral force with crews of different nationalities “mixed manning”). For top officials in the State Department, that would mean the end of a British independent nuclear force, but that proved to be a tall order. [For an account of decision-making, see Document 18].

As the discussion covered by this memcon indicates, Macmillan was frustrated by the U.S. cancellation but was determined that Britain “stay in the nuclear club or he would resign, and we would have a permanent series of [Gaitskells]” to contend with (a reference to British Labour Party leader Hugh Gaitskell). The two sides, however, moved toward an understanding about Polaris and possible British participation in an MLF under NATO auspices. To stay in the “club” and to preserve ultimate British freedom of action, Macmillan was willing to assign British Polaris submarines to a NATO force as long as the “Queen had the ultimate power and right to draw back in the case of a dire emergency similar to that in 1940.” While the British were far from sold on MLF and never made an ironclad commitment, Kennedy agreed to the Polaris arrangement on the spot. By April 1963 Washington and London had signed off on a Polaris sales agreement to provide the missiles and supporting equipment, less the warhead, but with no direct link to British participation in an MLF agreement.

The copy published here has faint portion markings indicating the sections that were expurgated from the copy provided to the State Department. The complete version stayed at the White House (and later the Kennedy Library), while the expurgated version went to the State Department’s Conference Files. Apparently, White House officials believed that the State Department did not need to see the more candid exchanges, such as Kennedy’s chauvinistic banter about women, the various statements about Germany, and Macmillan’s digs at U.S. ideas about “mixed manning” on ships assigned to the MLF (“putting a British sailor on board ship to have tea with the Portuguese”).


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Source: RG 59, Policy Planning Council Records, 1963-1964, box 281, Europe 1963-1964


In the weeks after the Nassau conference, officials at the Pentagon prepared an inventory of nuclear forces assigned to NATO or in the possession of the British. The first page specifies nuclear forces that covered the SACEUR “threat list,” including U.S. missiles, strategic bombers, and fighter bombers, along with Dutch, Greek, and West German fighter bombers, all of which would have access to the nuclear stockpiles in their countries. In addition, according to the Pentagon, the British had 63 bombers assigned to SACEUR targets.

On the second page, the Pentagon enumerated U.S. and British strategic forces in “approximate” numbers only. The numbers of the British bombers and the nuclear weapons assigned to them are likely far from accurate. The Macmillan government’s goal of a force of 144 front-line nuclear-capable bombers by 1963 was substantially fewer than the 195 “V” bombers enumerated here. Later that year, the British followed through on their loose multilateral commitments at Nassau by assigning their “V” force for targeting by SACEUR, who already had a planning cell at SAC headquarters.[18]


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Source: John F. Kennedy School of Government Case Study; from original at Kennedy Presidential Library and Museum


Richard Neustadt’s report, commissioned by President Kennedy, remains the most comprehensive account to date of the Skybolt affair. When he prepared it, Neustadt had access to the relevant U.S. government files and interviewed top officials (if not Kennedy himself). He also had access to British officials and some British records. It has been retrospectively criticized, for example, for not looking at the possibility that the British used their leverage to instill a sense of guilt on the U.S. side so that Kennedy felt an obligation to find a replacement for Skybolt.[19]

However the Skybolt affair ought to be interpreted, Neustadt’s account is a valuable primary source because of his unparalleled access. For example, he shed light on the thinking of Secretary of State Dean Rusk who did not want the Skybolt cancellation to turn into a damaging crisis with London. As Rusk explained to subordinates who wanted to tie the British into Western Europe, “we have to have somebody to talk to in the world … we can’t talk to De Gaulle … or Adenauer; do you want to take Macmillan away and leave us nobody.” According to a report on a “dictabelt” (tape recording) sent from Paris, “The Secretary said he wasn’t against the special relationship until he could see something better to take its place.”


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Source: RG 59, Subject-Numeric Files, 1964-1966, DEF 12-5 UK-US


The U.S. Embassy reported on the follow-up on the Polaris sales agreement including organizational aspects and program costs. The Conservative government had decided that a force of five submarines (although Labour would later reduce the number to four) was necessary so that two submarines could be on patrol simultaneously. The keels for the first two submarines of the Resolution class had been laid earlier in the year and under the government’s schedule, the first submarine was to begin patrolling in June 1968. The missiles would carry Mk-2 re-entry vehicles, the multiple-warhead system used by U.S. Polaris A-3 SLBMs (although that was not mentioned in the report). The British would incorporate their own nuclear warhead in the Mk-2.

The month this report was prepared, October 1964, the Conservatives lost the election to the Labour Party, so the future of the Polaris program was up in the air. While Labour had campaigned against the Nassau agreement and an independent nuclear deterrent in favor of committing the V-bomber force to NATO, its leadership had not made any decisions. From the embassy’s perspective, cancelling Polaris would be the worst choice both for London and Washington, because of the financial penalties involved for cancellation and the harm to the U.S. balance of payments. [20]


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Source: DNSA; from RG 59, Bureau of Intelligence and Research, Reports Coordination and Review Staff, Research Memoranda, 1965-1966, box 155, REU-7-RM


Washington was still interested in the possibility of a nuclear multilateral force and both West Germany and the United Kingdom were central to any prospect for such an arrangement. The Johnson administration wanted Bonn and London to take the lead in developing proposals for such an organization before the U.S. would make any commitments. To estimate the prospects for British and West German action, State Department intelligence prepared a close review of the outlooks and interests of both governments. The detailed analysis of the United Kingdom includes an overview of British nuclear forces, noting the Labour Government’s decision to take steps to “prolong the effective life” of what INR believed was a force numbering 177 V-bombers. Labour also decided to move ahead with four Resolution class submarines, which meant that it could keep only one on patrol continuously.

The Labour Government was also looking at the role of nuclear weapons in supporting British interests in East Asia. For example, it had deployed V-bombers (not nuclear-armed) to deter Indonesian pressure on Malaysia. Moreover, the Wilson Government saw nuclear weapons as a “counterpoise” to China’s developing nuclear capability.

Although Labour politicians had once looked askance at Tory claims that nuclear weapons gave London a “seat at the top table” of international negotiations, now they thought differently. For the most part, the Labour Government was hewing to Conservatives’ nuclear policy: they were unlikely to throw away the nuclear “card” when Labour leaders were learning that “The key role that Britain is now playing in the Alliance nuclear discussion, and London's ability to influence its outcome, stem in good measure from the possession of a significant present and future nuclear capability.”

Labour was even more critical of the MLF proposal than the Conservatives had been, but it had advanced the idea of an Atlantic Nuclear Force (ANF) to share nuclear responsibility with non-nuclear members of NATO such as West Germany. Nevertheless, London would “avoid final commitments on questions involving British weapons and delivery systems in order to retain maximum options for the time when hard negotiations begin, if and when that point is reached.” If the ANF fell through, London was likely to commit the Polaris force to NATO, as envisaged in the Nassau Agreement; it would, however, avoid anything that weakened the special relationship with the United States and ultimate British control of the deterrent in a defense emergency.


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Source: CIA FOIA Reading Room


In 1965 the U.S. government began to tighten the sharing of nuclear weapons information with London because defense officials saw the British as a less valuable nuclear partner, in light of the decision to end nuclear testing and stop development work on nuclear warheads.[21] Three years later, the Lyndon Johnson administration had to decide whether to exercise an option to terminate the 1958 nuclear cooperation agreement with London or to let it continue for five more years. A decision to let things stand was reached near the end of 1968 (which Congress would approve), but as this record of discussion indicates, senior State and Defense officials were already inclined to let the agreement continue and believed that it was in the U.S. interest that the British have a “first-rate capability.” Nevertheless, the meaning of “first-rate” would be somewhat circumscribed because information sharing would be limited to “what seems reasonably required to keep their force viable in the 1970s.” New weapons and delivery systems, such as Poseidon, would be subject to negotiations on a “case-by-case” basis.


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Source: DNSA; from Record Group 84, Top Secret Foreign Service Post Files, Embassy London, 1965-1976, box 1, 1969


As soon as they started sailing Polaris submarines, the British began worrying that anti-ballistic missiles could threaten their ability to strike targets in the Soviet Union. Interested in upgrading their warheads, the British looked at a U.S. design, Antelope, that had been considered as an alternative to Poseidon. It would reduce vulnerability to ABMs by hardening the reentry vehicle against nuclear effects and by using penetration aids. This record of a meeting at the office of John S. Foster, director of defense research and engineering, provides the lead-up to a U.S.-U.K. memorandum of understanding concerning British participation in U.S. underground weapons effects tests and U.S. appraisal of Super Antelope, a proposed warhead for the British Polaris.[22] The memorandum pointed to significant divisions between senior British defense officials, Solly Zuckerman vs. William Cook, over whether British Polaris should be able to ride through ABM defenses and strike Moscow independently of a U.S. retaliatory strike.


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Source: DNSA, from RG 59, Subject-Numeric Files, POL UK-US


On the U.S. side of the documentation, this conversation is an early example of the British sharing their “Moscow criterion” priority with U.S. officials. The British closely followed the SALT negotiations, especially on anti-ballistic missile systems, because the Soviet ABM could jeopardize the ability of “small nuclear forces” to strike Moscow and other urban targets. Especially worrisome to the British were tactics that the Soviet ABM could use to counter incoming missiles. The British had been worried that the U.S. was more interested in limiting Soviet Hen House radars, used for missile warning purposes, than to limiting the Dog House radars, used to track and analyze incoming “objects,” but the U.S. team assured them otherwise.


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Source: DNSA, from RG 59, Subject-Numeric Files, Top Secret files, box 1, AE 1-1 UK-US


This document concerns an interagency report with recommendations on U.S. assistance in improving British SLBMs. In 1970, the British informed Washington that the Cabinet had decided to initiate a “Project Definition study of ways to improve the hardness and penetration capability” of the Polaris warhead “to penetrate Soviet ABM defenses and strike Moscow, or other major cities in the Western USSR” [see Document 25]. To carry the Super Antelope study forward, the British asked for U.S. advice and assistance. As the request raised important questions about U.S.-U.K. relations and nuclear cooperation, National Security Advisor Henry Kissinger asked for an interagency report under National Security Study Memorandum 123. Both President Richard Nixon and Kissinger were less concerned than their predecessors about “independent centers of decision” (as long as they were allies) and had no problem with secret assistance to the British nuclear program.[23]

The present document provides an overview, if not the details, of the major findings of the study, which found that a refusal of U.S. aid to Super Antelope would have a “major adverse impact” on Anglo-American relations. Consistent with this, the U.S. would assist the Project Definition phase, but with “rather tight control” to keep British “visibility” low in some of the areas where they proposed cooperation, such as at underground test sites or missile flight test facilities [see Document 25]. Moreover, the report suggested that the U.S. confirm to the British “at the diplomatic level that an explicit governmental decision has been made to approve [their] request.” That would demonstrate that the U.S. recognized “the significance of the cooperation we are pursuing but it would also provide an opportunity … to point out for the record that we assume the British realize we can accept no responsibility for success or failure, since we have not participated in the formulation of the project.”


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Source: DNSA; Richard Nixon Presidential Library and Museum, National Security Council Institutional Files, box H-182, NSSM 123 (folder 2 of 2)


With this package of documents, Kissinger aide Hal Sonnenfeldt passed on the NSSM 123 report along with agency comments, his recommendations, and a memorandum that could be presented to President Nixon. Sonnenfeldt recommended option 2 (a) 37 [the options are presented on PDF pages 37-38] but with a little extra—the U.S. could consider support for post-Projection Definition work on a case-by-case basis. He pointed out several concerns, including “If we are not careful, it could get us into a Skybolt-type situation two years hence.” That is, a difficult problem with London could emerge if the U.S became more interested in promoting “Western European defense/nuclear cooperation” and began to curtail the U.S.-U.K. special nuclear relationship.

The memorandum that was prepared for Nixon pointed out the dilemma. Because the Defense Department had already held consultations with the British over Super Antelope “any negative decision at this time would surprise them” and have “repercussions on the whole range of U.S.-U.K. relations, including your relationship with Prime Minister Heath.” In addition, it was in the U.S. interest to help the British modernize their force because it “contributes to Western deterrent strength.” Yet, the U.S. did not want to “deepen our cooperation with the British to the point where it would virtually foreclose possible Anglo-French or West European defense cooperation.” Kissinger presented Nixon a National Security Decision Memorandum, NSDM 124, which approved initial assistance to Super Antelope.

Sonnenfeldt included a summary of the larger NSSM 123 study, which noted that notwithstanding the Defense Department’s assumption that it could decide on its own, “U.S.-U.K. nuclear relations are Presidential business.” According to the report, the British made a “relatively small contribution to U.S. strategic objectives” because their target coverage, which focused on military targets, was about seven percent of the total. Given British insistence on a right to withdraw their nuclear forces from NATO commitments, it was likely that London had “independent” plans for nuclear strikes aimed at urban targets. Since the goal of Super Antelope was to breach the ABM system protecting Moscow, it was less suited for NATO strike plans than for an “independent UK launch capability.” Use of the latter would be inconsistent with U.S. policy because it could diminish Washington’s “control over the initiation and conduct of nuclear war.”


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Source: DNSA; from RG 59, Subject-Numeric Files, 1970-1973, Top Secret Files, box 1, AE 1-1 UK-US


Commenting on an unidentified paper by Joseph Kendrick, Policy Planning Council official Seymour Weiss mentioned British interest in a low number of Soviet ABMs because “they want to be sure to be able to penetrate to Moscow or at least to have the Soviets believe that they have such a capability.” Noting the British effort to upgrade their Polaris missiles, Weiss assumed that they wanted to enhance their ability to strike Soviet urban targets. He also thought it was important that the British had qualified their Polaris submarine commitment to NATO by preserving the right to withdraw it as a matter of “supreme national interest.” In that connection, Weiss “would not, myself, bet against the existence of a British national targeting option of counter-value strikes in the event the US did not activate SIOP and the British felt their ‘supreme national interest’ in jeopardy.”

Weiss was correct, because independent target planning had been important to the British since the 1950s, and Moscow, among other urban centers, was a priority target. As part of the idea of an independent capability, Labour Defense Minister Denis Healey wanted a “system which could commit the Americans if we used [nuclear forces],” seeing that as “kind of [an] insurance policy” and a “catalytic deterrent.” Moreover, British forces would serve as a kind of “reassurance”: if the U.S. became “isolationist” they could act as a “tripwire” that would force Moscow to “pause” before making an attack.[24]


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Source: DNSA, RG 59, Subject-Numeric Files, POL UK-US


The status of ABMs in the SALT negotiations remained a concern for the British. Until they improved their missile force, an agreement that left the Soviets with more than 200 launchers would impair the U.K.’s capability to penetrate missile defenses. As it turned out, the ABM treaty left the signatories with the right to two sites, at their national capitals and at an ICBM base with 100 launchers stationed at each location, which indicated that the British would need a warhead, Super Antelope, or an alternative, that could surmount that challenge. [25]



Note: Thanks to Professor Matthew Jones, London School of Economics, for valuable comments on an earlier version of this posting.



[1]. See, for example, editorials by the Arms Control Association and on the Website of BASIC, the British-American Security Information Council, as well as comments by Des Browne, vice chair of the Nuclear Threat Initiative [NTI]. See also Michael Krepon, “Britain Increases Its Defense Spending and Shortchanges Its Future, Arms Control Wonk, 22 March 2021 and Hans Kristensen, “British Defense Review Ends Nuclear Reductions Era,” 17 March 2021, Federation of American Scientists.

[2]. Lorna Arnold, “The History of Nuclear Weapons: The Frisch-Peierls Memorandum on the Possible Construction of Atomic Bombs of February 1940” Cold War History 3 (2003): 111-126.

[3] . For postwar, British official thinking about nuclear weapons, see John Baylis and Kristan Stoddart, “The British Nuclear Experience: The Role of Ideas and Beliefs (Part One),” Diplomacy and Statecraft 23 (2012): 331-346. For the official history of the program, see Margaret Gowing, Independence and Deterrence: Britain and Atomic Energy 1945–52, two volumes (London: Macmillan, 1974). For an overview, see Matthew Jones, The Official History of the UK Strategic Nuclear Deterrent: Volume I: From the V-Bombers Era to the Arrival of Polaris, 1945-1964 (London: Routledge, 2017), chapter 1. On the British H-bomb, see Lorna Arnold with Katherine Pyne, Britain and the H-Bomb (New York: Palgrave, 2001).

[4] . For the story of “Project E,” see Ken Young, The American Bomb in Britain: U.S. Air Forces’ Strategic Presence,1946-1964 (Manchester: Manchester University Press, 2016) and Justin Bronk, “Britain’s ‘Independent’ V-Bomber Force and US Nuclear Weapons, 1957–1962,” Journal of Strategic Studies 37 (2014): 974-997. See also John Baylis, “Exchanging Nuclear Secrets: Laying the Foundations of the Anglo-American Nuclear Relationship,” Diplomatic History 25 (2001): 33-61.

[5] . For the importance to British elites of nuclear forces and the special nuclear relationship with the U.S., see Nick Ritchie, “Relinquishing Nuclear Weapons: Identities, Networks and the British Bomb,” International Affairs (2010): 465-487

[6] . For Macmillan’s grave concern about the impact of the accident on nuclear relations with Washington, see Lorna Arnold, Windscale 1957: Anatomy of a Nuclear Accident (New York: St. Martin’s Press, 1992), 83-85.

[7]. Eisenhower was less than enthusiastic on the information exchanges, see Ian Clark, Nuclear Diplomacy and the Special Relationship: Britain’s Deterrent and America, 1957-1962 (Oxford, Clarendon Press, 1994), 84-86.

[8] . See also Lorna Arnold, Britain and the H-Bomb, Part IV, for the 1957 tests.

[9] . Baylis, “Exchanging Nuclear Secrets,” 45-46. See also Clark, Nuclear Diplomacy, 85-92.

[10] . For the 1951 understanding and its context, see Matthew Jones, “Great Britain, the United States, and Consultation over the Use of the Atomic Bomb, 1950-1954,” The Historical Journal 54 (2011): 797-828.

[11] . For the Murphy-Dean negotiations, see Stephen Twigge and Len Scott, Planning Armageddon: Britain, the United States, and the Command of Western Nuclear Forces, 1945-1964 (Amsterdam: Harwood Academic Publishers, 2000), 326-333. For the operational implications of Murphy-Dean, see Robert S. Hopkins, Strategic Air Command in the UK: SAC Operations 1946–1992.(Manchester: Hikoki Publications: 2019), 21-23.

[12] . For the 1958 negotiations, see Jones, The Official History, 100-102 and, 114-118, and Arnold, Britain and the H-Bomb, 203-206.

[13] . Clark, Nuclear Diplomacy, 267-280. For the cancellation of Blue Streak, see Jones, The Official History, Vol. 1, 191-210. Once the Thor warheads were deployed to the missile sites, SAC exercised control over them through a Launch Control Officer at each location. See Hopkins, Strategic Air Command in the UK, 193-195.

[14] . Justin Bronk, “Britain’s ‘Independent’ V-Bomber Force and US

Nuclear Weapons, 1957–1962,” Journal of Strategic Studies 37 (2014): 994.

[15] . Matthew Jones, “Prelude to the Skybolt Crisis: The Kennedy Administration’s Approach to British and French Strategic Nuclear Policies in 1962,” Journal of Cold War Studies 21 (2019): 86. Whether the Bomber Command was capable of undertaking that mission is another story; see Bronk, “Britain’s Independent’ V-Bomber Force and US Nuclear Weapons, 1957–1962,” Journal of Strategic Studies 37 (2014): 974-997.

[16] Jones, “Prelude to the Skybolt Crisis,” 90-95, for further discussion of the McNamara memorandum.

[17] . Also discussed in Jones, “Prelude to the Skybolt Crisis,” 98.

[18] . Young, The American Bomb in Britain, 213; Stephen Twigge and Len Scott, Planning Armageddon, 138-139.

[19] . For accounts of the Skybolt affair, see Clark, Nuclear Diplomacy, chapters 10 and 11; Jones, The Official History, Vol. I, chapters 6, 9, and 10, and Ken Young, “The Skybolt Crisis of 1962: Muddle or Mischief?,” The Journal of Strategic Studies 27 (2004): 614-635, whose take on British intentions parallels Clark’s. Also useful is Lawrence Kaplan, Ronald D. Landa, and Edward J. Drea, History of the Office of the Secretary of Defense, Volume V: The McNamara Ascendency, 1961–1965 (Washington, D.C: Historical Office of the Office of Secretary of Defense, 2006), 375-384.

[20] . For a detailed account of the development of the British Polaris submarine program and subsequent financial and vulnerability problems, see Matthew Jones, The Official History of the UK Strategic Nuclear Deterrent: Volume II: The Labour Government and the Polaris Programme, 1964–1970 (London: Routledge, 2017).

[21] . Jones, The Official History, Vol. II, 52-58, 63-64, 69-74, 357-61, 391-394, and 431-434.

[22] . Jones, The Official History, Vol. II, 479-481. For the late 1960s, see also the pioneering study by John Baylis and Kristan Stoddart, “Britain and the Chevaline Project: The Hidden Nuclear Programme, 1967–82,” The Journal of Strategic Studies 26 (2003): 127-131

[23] . Jones, The Official History, Vol. II, 440–441, 445, 447, 483, and 490–494.

[24] . Baylis and Stoddart, “The British Nuclear Experience: The Role of Ideas and Beliefs (Part One),” 343, and Kristan Stoddart and John Baylis, “The British Nuclear Experience: The Role of Beliefs, Culture, and Status (Part Two),” Diplomacy and Statecraft 23 (2012): 494, 498. See also Jones, The Official History, Vol. I, 50-54, and The Official History Vol. II, 248–250, 287, and 301.

[25] . For “Super Antelope” in the early 1970s, see Baylis and Stoddart, “Britain and the Chevaline Project;” Helen Parr, “The British Decision to Upgrade Polaris, 1970–4,” Contemporary European History 22 (2013): 253-274; and Thomas Robb, “Antelope, Poseidon or a Hybrid: The Upgrading of the British Strategic Nuclear Deterrent, 1970–1974,” The Journal of Strategic Studies 33 (2010): 797-817.