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Disarmament Diplomacy No. 76, Cover design by Paul Aston

Disarmament Diplomacy

Issue No. 76, March/April 2004

In The News (or Should Be)

US-UK Nuclear Weapons Cooperation Up for Renewal

"Proliferators must not be allowed to cynically manipulate the NPT..."
President George W. Bush, February 11, 2004.

When President Bush announced measures to strengthen international efforts to prevent proliferation of weapons of mass destruction in February 2004, one issue that was not mentioned was proliferation between nuclear weapon states. Talks are currently underway to renew and update the 1958 Mutual Defence Agreement, which provides the basis for extensive nuclear collaboration between the United States and Britain, despite questions about whether this cooperation is compatible with the NPT.

Britain is keen to get the Mutual Defence Agreement renewed as it intends to make a decision on whether or not to replace the UK's Trident nuclear weapon system following the next UK General Election (which must be held by June 2006). It would be extremely difficult and expensive for Britain even to maintain its existing Trident system, let alone to develop and build a new nuclear weapon system and its associated infrastructure without extensive help from the United States.

The 1958 Mutual Defence Agreement

The 1958 Mutual Defence Agreement covers all aspects of nuclear weapons design, development and maintenance. Under this unique agreement, the US and the UK exchange classified information with the objective of improving each party's "atomic weapon design, development, and fabrication capability". Although the US has nuclear cooperation agreements with a range of other countries, including France and those NATO countries that participate in nuclear sharing arrangements, the US-UK agreement is the most comprehensive by far.

The Agreement covers development of defence plans; training personnel in the use and defence against nuclear weapons; evaluation of enemy capabilities; development of nuclear delivery systems; and research, development and design of military reactors. The agreement also provides for the transfer of special nuclear material (i.e. plutonium or highly enriched uranium), components, and equipment between the two countries.

Current US-UK Cooperation

The UK currently deploys the US nuclear weapon system, Trident, using British-made submarines and an ostensibly British-designed warhead. The UK Trident uses Trident II D5 missiles from the US missile pool, which are manufactured, tested and serviced in the United States. UK Trident submarines collect the missiles from the US Trident submarine base at Kings Bay, Georgia. The missiles are tested at the US missile test range off the coast of Florida. The UK Trident submarines are assigned to NATO and rely on US satellites for targeting.

Britain's Trident warhead is believed to be closely based on the American W76 warhead and was tested at the US Nevada test site. The US and the UK cooperate closely on stockpile stewardship and maintenance of Trident, including extensive collaboration between the UK's Atomic Weapons Establishment and the US nuclear weapons laboratories.

There are regular flights between the US and the UK, which are believed to be transporting special nuclear materials (plutonium and/or highly enriched uranium), and possibly other nuclear weapon components for research and testing purposes.

The future of US-UK Nuclear Cooperation

Britain's Atomic Weapons Establishment (AWE) continues to maintain a "minimum capability to design and produce a successor to Trident should this prove necessary". In reality, however, if the UK decides to go ahead with a replacement for Trident, it is unlikely to choose anything that would not be identical (or very nearly) with an American nuclear weapon system.

When the British government decided to procure the Trident II D5 missile in the early 1980s, one of the key criteria was "commonality" with the US. Britain had previously intended to buy the Trident I C4 missile, but when the US phased out the C4, the option was ruled out on the grounds of "logistical, operational and financial penalties" were the UK to try to maintain the system on its own. Government documents from the time state that "as a unique system [the C4's] ability to remain so for further 25 years or more without remotoring or other deep refurbishment must be questionable... The costs and technical risks associated with such programmes to the United Kingdom, acting alone, are impossible to quantify so far ahead, but would be high by any standards... our experience of the Chevaline system shows just how expensive the resolution of problems in this field by programmes unique to the United Kingdom can be."1 To remain a nuclear weapon state, the UK clearly depends to a high degree on US help.

This dependence has serious implications for British foreign policy too, almost certainly contributing to the reluctance of UK Governments - whether Labour or Conservative - to criticise US policy and actions. Britain's 'independent nuclear deterrent' requires the UK to be sure to fall quickly into line with US nuclear planning and doctrine.

The Bush administration and the US nuclear weapons laboratories are actively considering plans for a new generation of nuclear weapons, including 'bunker busters' and 'mini-nukes', possibly involving a renewal of US nuclear testing. Although the British government has stated that it has no intention of developing 'mini-nukes', cooperation between the weapons laboratories, provided for under the Mutual Defence Agreement leaves that option open for the future.

NPT Compliance: A Question of Interpretation?

The question of US-UK nuclear cooperation has been raised on a number of occasions including during the 1995 NPT Review Conference, in Main Committee I, under the review of Articles I and II. Some non-nuclear weapon States parties to the Treaty, led by Mexico, attempted to raise the issue, with the consequence that the draft report from Main Committee I noted that "among States parties there are variations in the interpretation of certain aspects of articles I and II which need clarification, especially regarding the obligations of nuclear-weapon States parties among themselves... which may have resulted in transfer of nuclear weapons in violation of the spirit and objective of article I."2

Article I of the NPT states that:

"Each nuclear-weapon State Party to the Treaty undertakes not to transfer to any recipient whatsoever nuclear weapons or other nuclear explosive devices or control over such weapons or explosive devices directly, or indirectly..."

Although the US and Britain declared themselves to be in full compliance with Article I, the Non-Aligned Movement proposed in a working paper that, "The Conference underlines the need for nuclear weapon States to remain in compliance with the letter and the spirit of Article I. The Conference further reiterates that the prohibition of transfer of nuclear weapons and nuclear explosive devices includes transfers between nuclear-weapon States."3

The US and the UK interpretation is that the 1958 Mutual Defence Agreement is an "existing security arrangement" that involves no transfer of actual nuclear weapons and that therefore it is fully in compliance with Article I. Whilst the US and the UK were clearly careful when the NPT was negotiated in the 1960s to ensure that a wording was found for Article I that would not explicitly rule out nuclear cooperation, states parties' interpretation of the NPT has changed, and the objections by non nuclear weapon states parties in 1995 and 2000 show that they do not regard the US-UK interpretation as appropriate for the present security environment.

Closing the Loopholes

In February 2004, President Bush announced plans to close the loophole in the NPT that has been used by countries such as Iran and North Korea to acquire nuclear materials and infrastructure, so long as they did not acquire an actual nuclear weapon. Britain and the US exploit a similar loophole in Article I to exchange nuclear material, components, and information, enabling Britain essentially to procure and maintain a US nuclear weapon system.

The US interpretation of the NPT has always been that "The treaty deals only with what is prohibited, not with what is permitted." This interpretation has been used by the US to justify a range of nuclear cooperation programmes with NATO allies, including Britain. Such a loose interpretation would no doubt also be convenient for some states to justify acquiring nuclear materials and infrastructure, provided that no actual nuclear device is assembled. This permissive and discriminatory interpretation of the NPT is no longer appropriate if the aim of the Treaty is genuinely to prevent nuclear proliferation.

President Bush states that, "there is a consensus among nations that proliferation cannot be tolerated." Proliferation between nuclear weapon states should likewise not be tolerated.


1. 'The United Kingdom Trident Programme', Ministry of Defence, Cmnd8517, March 1982.

2. 'Report of Main Committee I', NPT/CONF.1995/MC.I/1, May 8, 1995. The 1995 Review Conference failed to adopt a final document, so this report was never formally agreed by states parties.

3. 'Review of Articles I and II and First to Third Preambular Paragraphs, Language proposed by the members of the Movement of Non-Aligned Countries parties to the Treaty,' NPT/CONF.1995/MC.I/WP.9, May 8, 1995.

Nicola Butler

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