A Note on British Nuclear Forces, May 2002
Britain commenced its nuclear weapons programme shortly after the end of the Second World War and tested a fission (atom) bomb in October 1952 and a fusion (hydrogen) bomb in May 1957. By the end of the 1950s Britain had developed a strategic nuclear force based on the V-bomber medium-range jet bombers, the Valiant, Victor and Vulcan.
From the mid-1960s, Britain began to develop a force of ballistic missile submarines capable of deploying the US Polaris submarine-launched ballistic missile (SLBM). The first such submarine, Resolution, commenced patrol in June 1968, and control of the UK strategic nuclear force passed to the Royal Navy in July the following year.
Britain also developed a range of tactical nuclear weapons, principally bombs, that were deployed on a number of land-based and carrier-based strike aircraft from the late-1950s onwards. These included the Scimitar, Buccaneer, Jaguar and Sea Harrier, and the Lynx and Sea King helicopters. In addition, US-made nuclear depth bombs were carried by Nimrod maritime patrol aircraft and US-made Lance missiles and nuclear warheads, and nuclear artillery shells, were deployed with the British Army.
At its peak, in the early 1980s, Britain deployed some 400 of its own nuclear weapons together with several scores of US nuclear weapons. With the ending of the Cold War, the majority of the types of nuclear weapons declined fairly rapidly, but two major types of British nuclear weapon remained in service until the late 1990s, the Polaris SLBM and the WE-177 tactical nuclear bomb. Trident In July 1980, the UK government announced that it would purchase the US Lockheed Trident C4 SLBM to be deployed in a new class of British-built ballistic missile submarines to replace the Polaris system during the 1990s. Two years later, it was announced that the UK would purchase the more advanced Trident D5 missile system, with a substantially greater range and improved accuracy.
The first submarine, Vanguard, was ordered in April 1986 from Vickers Engineering and Shipbuilding Ltd (VSEL) of Barrow, Cumbria. As with Polaris, the trident submarines would be based at RN Faslane, with the missile and warhead storage location being the Royal Navy Armaments Depot at Coulport. Refits and repairs would be carried out at the naval dockyard at Rosyth on the Firth of Forth. Since February 2002, these have been undertaken at Devonport.
The Trident system was originally intended to constitute just the strategic nuclear force for Britain, but it was subsequently decided to phase out Britain’s WE-177 tactical bombs carried on Tornado strike aircraft. As a consequence, a number of warheads for the Trident missile system have been adapted to produce a lower explosive force so that they can be used in a tactical or “sub-strategic” role.
From April 1998, the new Trident submarines therefore constituted Britain’s strategic and sub-strategic nuclear forces.
The final Polaris submarine, Repulse, completed its last patrol on August 1996, the first of the new Trident submarines, Vanguard, having commenced patrols in December 1994. The second, Victorious, entered service in December 1995, followed by Vigilant and the final boat, Vengeance, which was deployed in 1999.
Each boat can carry up to 16 Trident D5 missiles, each with a range of about 5,000 miles. Britain does not actually own the missiles but has “title” to 58 missiles from the much larger pool of missiles built for the US and Royal Navies. The Trident system is very much more accurate, and has a much longer range, than the Polaris system it replaces.
The thermonuclear warhead carried by the missile is of UK manufacture but is based closely on a US design, the W76 warhead. Britain’s version is believed to have a similar explosive power to the W76 – 100 kilotons, equivalent to 100,000 tons of conventional high explosive. The bomb that destroyed Hiroshima and killed an estimated 80,000-100,000 people on 6 August 1945, was designed to yield an explosive force of 20 kilotons, but is believed to have detonated incompletely, at 13 kilotons. In crude terms, a single Trident warhead is roughly eight times as powerful as the Hiroshima bomb.
Plutonium recycled from the obsolete Polaris nuclear warheads has been incorporated into Trident warheads, and it is estimated that Britain will retain a stockpile of around 185 warheads for its Trident force. While this is slightly less than half of the number at the peak of the Cold War, this figure is somewhat misleading, because of the substantially increased accuracy and range of the system.
A proportion of the Trident warheads, possibly about one-sixth, will be deployed as sub-strategic or tactical warheads, by configuring them to detonate as “boosted primaries” (current warheads have a “primary” nuclear explosion which is “boosted” to initiate a more powerful “secondary” detonation). The sub-strategic warhead is likely to have an explosive yield similar to that of the older WE-177 tactical nuclear bomb, around 5-10 kilotons, rather less than the Hiroshima bomb.
The present government has announced that each Trident submarine on patrol will carry up to 48 warheads, likely to comprise a mix of up to six single-warhead sub-strategic missiles and around 10 multiple-warhead strategic missiles. Missiles fitted with several warheads are capable of delivering them to quite different targets over distances of hundreds of miles. This is because the missiles are fitted with Multiple Independtly-Targetable Re-entry Vehicles (MIRVs), which can alter course during the flight path, releasing warheads towards different targets. The Polaris system was not able to do this.
Research and development, and some construction, of Trident warheads is undertaken at the Atomic Weapons Establishment at Aldermaston in Berkshire, and at a nearby centre at Burghfield. Nuclear weapons are moved between these centres and RNAD Coulport by road. Targeting Policy Although Britain is in a position to use its nuclear weapons without reference to its NATO allies, the common practice has been to contribute its forces to NATO. This practice continues with Trident, both in relation to the strategic and sub-strategic versions of the missile.
Until the late-1960s, NATO’s nuclear policy was codified in a document MC14/2, known as the “tripwire” policy. This envisaged a massive nuclear response to any Soviet initiation of war and was developed when NATO had a massive nuclear superiority over the Soviet Union. By the early 1960s, the United States had developed numerous tactical nuclear weapons and was leaning towards the use of such weapons in nuclear exchanges which might fall short of all-out nuclear war.
By the late-1960s, the tripwire policy was becoming untenable as the USSR began to match NATO’s nuclear forces. NATO therefore developed a new policy, commonly termed flexible response, codified in document MC14/3 of 16 January 1968. This was entitled the Overall Strategic Concept for the Defence of the NATO Area, and covered general conventional and nuclear policy, with the details of the latter developed by the Nuclear Activities Branch of the Supreme Headquarters, Allied Powers in Europe (SHAPE), at Mons in Belgium.
Flexible response envisaged two levels of nuclear employment, selective use and general response. The former involved the use of a limited number of nuclear warheads against Soviet troops and their logistic support, in the belief that their advance could be halted without escalation to all-out nuclear war. Numbers of warheads used might range from a handful up to around a hundred, depending on circumstances. If the policy failed and the conflict escalated, NATO would move to general response, which amounted to all-out nuclear war.
The NATO policy of the first use of nuclear weapons was not promoted widely in public, where all the emphasis was placed on nuclear weapons as an ultimate deterrent. Even so, the policy was made clear on relatively rare occasions, as in this example of evidence from the Ministry of Defence to a Parliamentary Select Committee in 1988:
The fundamental objective of maintaining the capability for selective sub-strategic use of theatre weapons is political – to demonstrate in advance that NATO has the capability and will to use nuclear weapons in a deliberate, politically-controlled way with the objective of restoring deterrence by inducing the aggressor to terminate his aggression and withdraw.
With the ending of the Cold War, there was some easing of NATO nuclear policy, with withdrawal of a substantial proportion of NATO nuclear weapons from Western Europe as the Soviet Union withdrew from Eastern Europe, and the possibility of first use was considered increasingly unlikely, but not abandoned as a facet of NATO policy.
More recently, as Russian conventional forces have deteriorated dramatically with the decline of the Russian economy and the collapse of the defence budget, the Russian armed forces have come increasingly to rely on nuclear weapons for their security. At its Washington Summit in April 1999, NATO endorsed its policy of maintaining sub-strategic nuclear forces in Europe.
British Independent Targeting Since the 1950s, Britain has deployed nuclear weapons on many occasions outside the immediate NATO area of Western and Southern Europe and the North Atlantic. This has included the Middle East, South-East Asia, the Indian Ocean and during the Falklands War. This raises the question as to whether sub-strategic, or indeed strategic, Trident warheads, might be used independently of NATO.
Britain reserves this right, and one of the more detailed assessments of the range of options for sub-strategic Trident warheads was made in the authoritative military journal International Defense Review in 1994:
At what might be called the “upper end” of the usage spectrum, they could be used in a conflict involving large-scale forces (including British ground and air forces), such as the 1990-91 Gulf War, to reply to an enemy nuclear strike. Secondly, they could be used in a similar setting, but to reply to enemy use of weapons of mass destruction, such as bacteriological or chemical weapons, for which the British possess no like-for-like retaliatory capability. Thirdly, they could be used in a demonstrative role: i.e. aimed at a non-critical uninhabited area, with the message that if the country concerned continued on its present course of action, nuclear weapons would be aimed at a high-priority target. Finally, there is the punitive role, where a country has committed an act, despite specific warnings that to do so would incur a nuclear strike.
It is worth noting that three of the four circumstances envisaged involve the first use of nuclear weapons by Britain.
There has been concern expressed in parliament that the government has not been sufficiently clear about the circumstances under which British nuclear weapons would be used in post-Cold War circumstances. For example, the House of Commons Defence Select Committee noted, in 1998:
We regret that there has been no restatement of nuclear policy since the speech of the then Secretary of State in 1993; the SDR [Strategic Defence Review] does not provide a new statement of the government’s nuclear deterrent posture in the present strategic situation within which the sub-strategic role of Trident could be clarified. We recommend the clarification of both the UK’s strategic and sub-strategic policy.
This was, in part, in response to comments made to the Committee by the then Secretary of State for Defence, Mr (now Lord) Robertson. He had told the committee that the sub-strategic option was “an option available that is other than guaranteed to lead to a full scale nuclear exchange”. He envisaged that a nuclear-armed country might wish to “…use a sub-strategic weapon making it clear that it is sub-strategic in order to show that … if the attack continues [the country] would then go to the full strategic strike,” and that this would give a chance to “stop the escalation on the lower point of the ladder”.
This statement indicated that “a country”, such as Britain, could consider using nuclear weapons without initiating an all-out nuclear war, and that the government therefore appeared to accept the view that a limited nuclear war could be fought and won. It was evidently not the clear statement that the Committee sought, and it did not indicate the circumstances in which such weapons might be used. In particular, it did not appear to relate to whether Britain or British forces had already been attacked with nuclear weapons, or whether nuclear weapons would be used first in response to other circumstances.
At the same time, there had been no evidence to suggest that Britain had moved away from the nuclear posture of the Cold War era that included the possibility of using nuclear weapons first. On 20 March, 2002, the present Secretary of State for Defence, Mr Hoon, was questioned by members of the Select Committee and appeared to indicate that Britain maintained this policy. In relation to a state such as Iraq he said that “They can be absolutely confident that in the right conditions we would be willing to use our nuclear weapons.”
This exchange did not make clear whether this would be in response to a nuclear attack initiated by a state such as Iraq, but Mr Hoon was questioned on this point on 24 March on the Jonathan Dimbleby Programme on ITV. He was asked whether nuclear use might be in response to non-nuclear weapons such as chemical or biological weapons. He replied:
Let me make it clear the long-standing British government policy that if our forces if our people were threatened by weapons of mass destruction we would reserve the right to use appropriate proportionate responses which might…might in extreme circumstances include the use of nuclear weapons.
Later in the exchange, Mr Hoon made it clear that he could envisage circumstances in which British nuclear weapons were used in response to chemical or biological weapons. He was later asked by Mr Dimbleby:
But you would only use Britain’s weapon of mass destruction after an attack by Saddam Hussein using weapons of mass destruction?
Mr Hoon replied:
Clearly if there were strong evidence of an imminent attack if we knew that an attack was about to occur and we could use our weapons to protect against it.
The implication of this is clear – that there are circumstances where Britain would consider using nuclear weapons in response to a non-nuclear attack involving chemical or biological weapons and would even consider using nuclear weapons to pre-empt such an attack.
Conclusion Britain has deployed nuclear forces for over forty years. For most of that time, they have been primarily committed to NATO, which has maintained a nuclear targeting posture that includes the first use of nuclear weapons. Britain also retains the capability to use nuclear weapons independently. Although the publicly acknowledged “declaratory” policy remains one of “last resort” use of nuclear weapons, the “deployment” policy involves the idea of nuclear war-fighting that falls far short of an all-out nuclear war.
The Trident nuclear missile system has recently been deployed, and is expected to remain deployed for up to 25 years. It has the longest range and is the most accurate of any nuclear system deployed by Britain and, in its strategic configuration, each warhead has approximately eight times the destructive power of the Hiroshima bomb.
Professor of Peace Studies at Bradford University since 1992. Author of editor of 16 books and over 100 papers, mainly on international security issues, including four editions of the Guide to Nuclear Weapons. Co-author of the Directory of Nuclear, Biological and Chemical Arms and Disarmament, 1990. Lecturer at a number of UK defence colleges including the Royal College of Defence Studies and the Joint Services Command and Staff College. Professor Rogers has given evidence on a number of occasions to the House of Commons Select Committees on Foreign Affairs and Defence.