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. 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. 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. 
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.
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.”
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). 
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.
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.
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.”
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.
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.
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”).
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.
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.”
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. 
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.
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.”
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.”
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.