1958 US-UK Mutual Defence Agreement

The 1958 US-UK Mutual Defence Agreement is a bilateral treaty between the United States and the United Kingdom on nuclear weapons cooperation.

It was signed after the UK successfully tested its first hydrogen bomb during Operation Grapple. Whilst the US has nuclear cooperation agreements with other countries, including France and some NATO countries (see nuclear sharing), this agreement is by far the most comprehensive.

Details of the agreement

The agreement enables the US and the UK to exchange classified information with the objective of improving each party's "atomic weapon design, development, and fabrication capability". This includes 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 (e.g. plutonium, highly enriched uranium, tritium), components, and equipment between the two countries, and the transfer of "non-nuclear parts of atomic weapons" to the UK.

The agreement also covered the export of one complete US submarine nuclear propulsion plant and its enriched uranium fuel which was installed in the UK's first nuclear powered submarine, HMS "Dreadnought".

The UK was able to carry out underground nuclear tests at the US Nevada Test Site, the first taking place on 1 March 1962, following this agreement. [cite web|url=http://www.awe.co.uk/main_site/about_awe/history/timeline/1962/|title=UK Mounts First Underground Nuclear Test (UGT)|publisher=Atomic Weapons Establishment|accessdate=2007-03-15]

There are also confidential intelligence matters covered by the agreement. The UK government has not published these sections "because of the necessity for great confidentiality and because ... it might well assist proliferation". [cite web|url=http://www.publications.parliament.uk/pa/ld200304/ldhansrd/vo040622/text/40622-03.htm#st_27|title=UK-US Mutual Defence Agreement|work=Lords Hansard - column 1119|publisher=Hansard|date=2004-06-22|accessdate=2007-03-15]

This agreement replaced the earlier "Agreement for Cooperation Regarding Atomic Information for Mutual Defense Purposes" of 1955. A separate Polaris Sales Agreement was signed on April 6, 1963.

Assistance to UK nuclear weapons development

An early benefit of the agreement was to allow the UK to "Anglicise" the US W28 nuclear warhead as the Red Snow thermonuclear weapon for the Blue Steel missile by 1961. [cite web|url=http://www.awe.co.uk/main_site/about_awe/history/timeline/1961a/|title=Yellow Sun MK.2 Enters Service|publisher=Atomic Weapons Establishment|accessdate=2007-03-15] In 1974 a CIA proliferation assessment noted that "In many cases [Britain's sensitive technology in nuclear and missile fields] is based on technology received from the US and could not legitimately be passed on without US permission."citation|url=http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB240/snie.pdf|series=Special National Intelligence Estimate|title=Prospects for Further Proliferation of Nuclear Weapons|page=40|publisher=CIA|date=23 August 1974|id=SNIE 4-1-74|accessdate=2008-01-20]

The U.S. President authorised the transfer of "nuclear weapon parts" to the UK between at least the years 1975 to 1996. [cite web|url=http://www.ford.utexas.edu/library/document/nsdmnssm/nsdm276a.htm|title=National Security Decision Memorandum 276|publisher=U.S. National Security Council|date=1974-10-15|accessdate=2007-03-15] [cite web|url=http://bushlibrary.tamu.edu/research/pdfs/nsd/nsd61.pdf|title=National Security Directive 61|publisher=The White House|date=1991-07-02|accessdate=2007-03-15|format=PDF]

The UK National Audit Office noted that most of the UK Trident warhead development and production expenditure was incurred in the U.S. who would supply "certain warhead-related components". [cite paper|url=http://www.danplesch.net/articles/WMD/WMDMar10FINAL.pdf|title=The Future of Britain’s WMD|pages=15|author=Dan Plesch|publisher=Foreign Policy Centre|month=March | year=2006|accessdate=2007-03-15|format=PDF] cite book|title=Ministry of Defence and Property Services Agency: Control and Management of the Trident Programme|publisher=National Audit Office|date=29 June 1987|pages=para. 1.1, 3.27, A4.4|isbn=0102027889] Some of the fissile materials for the UK Trident warhead were purchased from the U.S. There is evidence that the warhead design of the British Trident system is similar to, or even based on, the US W76 warhead fitted in some US Navy Trident missiles, with design and blast model data supplied to the UK. [cite web|url=http://www.fas.org/blog/ssp/2006/12/britains_next_nuclear_era_1.php|title=Britain's Next Nuclear Era|publisher=Federation of American Scientists|date=2006-12-07|accessdate=2007-03-15] [cite web|url=http://www.fas.org/blog/ssp/images/W76req.pdf|title=Stockpile Stewardship Plan: Second Annual Update (FY 1999)|publisher=U.S. Department of Energy|month=April | year=1998|accessdate=2007-03-15|format=PDF]

pecial nuclear materials barter

Under the agreement 5.37 tonnes of UK produced plutonium was sent to the US in return for 6.7kg of tritium and 7.5 tonnes of highly enriched uranium over the period 1960-1979. A further 0.47 tonne of plutonium was swapped between the US and the UK for reasons that remain classified. [cite web|url=http://www.mod.uk/NR/rdonlyres/B31B4EF0-A584-4CC6-9B14-B5E89E6848F8/0/plutoniumandaldermaston.pdf|title=Plutonium and Aldermaston - an historical account|publisher=UK Ministry of Defence|date=2001-09-04|accessdate=2007-03-15|format=PDF] Some of the UK produced plutonium was used in 1962 by the US for the only known nuclear weapon test of reactor-grade plutonium . [cite web|url=http://permanent.access.gpo.gov/websites/osti.gov/www.osti.gov/html/osti/opennet/document/press/pc29.html|title=Additional Information Concerning Underground Nuclear Weapon Test of Reactor-Grade Plutonium|publisher=U.S. Department of Energy|month=June | year=1994|accessdate=2007-03-15]

The plutonium sent to the US included some produced in UK civil Magnox reactors, and the US gave assurances that this civil plutonium was not used in the US nuclear weapons program. It was used in civil programmes which included californium production and reactor research. However the UK did obtain military nuclear material in return, so via this barter UK civil power stations probably provided weapons material.

Controversy

Because the UK relies heavily on US assistance to maintain and develop its nuclear arsenal, this has raised questions about whether this level of cooperation is in breach of the Nuclear Non-Proliferation Treaty. Despite this, in 2004 negotiations were completed to extend the treaty for 10 years to 2014. [cite web|url=http://www.basicint.org/nuclear/MDAamend.htm|title=Amendment to the 1958 US-UK Mutual Defence Agreement (on nuclear weapons' cooperation)|publisher=British American Security Information Council|month=June | year=2004|accessdate=2007-03-15]

ee also

*Atomic Weapons Establishment
*Nassau agreement
*Nuclear weapons and the United Kingdom
*Nuclear weapons and the United States
*Quebec Agreement
*Special relationship

References

External links

* [http://www.basicint.org/nuclear/1958MDA.htm Full text of treaty]
* [http://www.acronym.org.uk/dd/dd77/77mda.htm Negotiations for extension to treaty]
* [http://www.awe.co.uk/main_site/about_awe/history/timeline/1958/ UK/US Agreement]
* [http://www.basicint.org/nuclear/MDAlegal.htm Mutual Defence Agreement and the Nuclear Non-Proliferation Treaty - Legal Opinion]
* [http://www.fas.org/news/uk/000414-uk2.htm Plutonium and Aldermaston - An Historical Account]
* [http://www.timesonline.co.uk/article/0,,60-1091224,00.html Ross Hesketh - publicised UK plutonium exports to USA]