Britain Discloses Size of Nuclear Stockpile: Who’s Next?

Britain says it has 225 nuclear warheads for its Trident submarine fleet.

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By Hans M. Kristensen

The new British government today followed the French and U.S. examples by disclosing its total military stockpile of nuclear weapons.

Foreign Secretary William Hague told the House of Commons that “the total number of warheads” in the “overall stockpile” will not exceed 225. Of those, “up to 160” are “operationally available” for deployment on Trident II missiles on British ballistic missile submarines.

The Royal Navy possesses four Vanguard-class nuclear-powered ballistic missile submarines (SSBNs), each of which can carry up to 16 U.S.-supplied Trident II long-range ballistic missiles. Each missile is thought to carry up to three UK-produced warheads closely resembling the U.S. 100-kt W76 warhead.

Stockpile and Arsenal

Whereas the United States declassified its entire stockpile history, the British government has only disclosed the current size of its stockpile, and only in the somewhat cryptic way: “the overall stockpile…will not exceed 225 warheads.”

That presumably means the stockpile actually contains 225 warheads, not that it might be smaller but “not exceed 225 warheads” even in the future.

That is 25 warheads more than the 200 Robert Norris and I have estimated in the past.

Of the 225 warheads, the government stated that it “will retain up to 160 operationally available warheads,” or as many as 71 percent of the entire inventory. There are only spaces for 144 warheads on Britain’s 50 Trident II SLBMs, of which 48 can be deployed on three operational SSBNs. The fourth boat is in refit at any given time and is not allocated missiles.

British Nuclear Weapons Stockpile 2010
With the British government’s declaration, it’s possible to make an estimated breakdown of the categories of nuclear warheads in the British stockpile.

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The “up to 160” probably refers to the 144 spaces plus a small number of spare warheads. The number of spares might increase if an SSBN deploys with less than its maximum capacity of 48 warheads. The remaining 65 warheads in the stockpile are for what is described as “routine processing, maintenance and logistic management.”

It is not yet possible to plot the history of the British nuclear stockpile with certainty. But if one assumes that the ratio of warheads in the non-operational reserve to the operationally available inventory has been roughly the same as today (approximately 1 x 2.5), then a simplistic projection of the stockpile looks like this:

British Nuclear Weapons Stockpile 1953-2010
The history of the British stockpile is unknown, but assuming the same percentage of warheads in reserve as today, a preliminary history can be plotted.

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The stockpile fluctuated considerably over the years with introduction and retirement of various weapon systems. The stockpile reached a peak in the late 1970s at nearly 500 warheads. After the Cold War, the stockpile decreased with the retirement of the WE-177 non-strategic nuclear bombs and depth charges for use by the air force and surface fleet. The last of the WE-177s was dismantled in August 1998.

Who’s Next?

Three of the five original nuclear weapon states have now disclosed the sizes of their military stockpiles of nuclear warheads. The pressure is increasing on the other nuclear weapon states to follow the good example.

The size of the Russian stockpile is unknown but Norris and I estimate Russia possesses 12,000 nuclear warheads, of which 4,600 might be operational. A Russian official recently told Reuters that Russia after ratification of the New START agreement “will likewise be able to consider disclosing the total number of Russia’s deployed strategic delivery vehicles and the warheads they can carry.” That would not be disclosing the size of the stockpile, but still be progress.

China’s stockpile is even more opaque, although Norris and I estimate it at approximately 240 warheads. That fits well with the declaration made by former British Defense Minister Des Browne in 2007, that the United Kingdom has “the smallest stockpile of any of the nuclear weapon states recognised under the NPT.”

Declarations from Indian and Pakistani would also be greatly welcomed. Israel is obviously a little more complicated because, well, it has yet to acknowledge that it has nuclear weapons, and North Korea doesn’t seem in the mood for goodwill gestures these days.

This publication was made possible by a grant from Carnegie Corporation of New York and Ploughshares Fund. The statements made and views expressed are solely the responsibility of the author.

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2 Responses to “Britain Discloses Size of Nuclear Stockpile: Who’s Next?”

  1. about May 30, 2010 at 8:29 pm #

    What’s the difference between “stockpile” and “arsenal”?

    Reply: Good question. Unfortunately, the answer often depends on who is writing. For the United States, the “stockpile” officially refers to the inventory of nuclear weapons that is officially in the custody of the Department of Defense. The “stockpile” is the total inventory of Pentagon “owned” weapons that are either deployed on/with active delivery systems (missiles and aircraft) or in military storage.

    Not included in the Pentagon’s stockpile is the inventory of nuclear weapons that the Department of Energy has custody of, which includes warheads that are either undergoing surveillance, repair, or life-extension work for later return to the Pentagon stockpile, or have been permanently retired from the Pentagon stockpile for dismantlement and disposition.

    The “arsenal” is sometimes used in the public debate to describe either the stockpile, total inventory (total stockpile and retired weapons), or just the immediately useable portion of the Pentagon stockpile that is deployed on/with missiles and aircraft.

    Other nuclear weapon states use “stockpile” and “arsenal” with no apparent definition. Not surprisingly, this makes it quite challenging to describe this information in publications. HK

  2. Peter Burt June 4, 2010 at 3:15 pm #

    Hello Hans, a very interesting analysis – thanks for posting it. Two quick points:

    1) What’s the rationale for the dip in warhead numbers in the mid 1990s?

    2) I’m wondering whether the portion of the graph from 2000 onwards is quite correct. The UK’s Atomic Weapons Establishment experienced significant difficulties in producing warheads for Trident in the 1990s because of commissioning problems with the A90 complex at Aldermaston. The conventional wisdom at the time was that AWE was only able to produce around 200 warheads. Might a likely scenario be that 225 were produced, and that when reductions in numbers of the UK’s operational warheads were announced in 1997 and 2007, the excess warheads were just retained in stock rather than decommissioned? We will have to wait until a further announcement from the UK government to be sure! :-)

    Reply: The fluctuations in the chart are from changes in delivery platforms. Yes, the actual stockpile level in 2000+ comes with considerable uncertainty. The curb might have been flatter. The 225-some were obviously produced, but how soon and what was retained or decommissioned at what point is unclear. The UK government should, as the United States has done, declassify the history of its stockpile. HK

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