Country Profiles: United Kingdom

UK flag
NPT: 1968
CTBT: 1998
First Test: 1952
First Hydrogen Bomb: 1958

Current number of nuclear warheads:
Strategic: ~195
Tactical: 0 (though some missiles can be adapted for tactical use)
Total: ~195

Last Updated: 2/27/02

Britain was the first country to study the feasibility of constructing nuclear weapons, and British physicists worked with American counterparts on the Manhattan Project during World War II. After the United States Atomic Energy Act of 1946 shut off Britain from United States nuclear weapons development, Britain sought to develop its own, a quest that was realized on October 3, 1952 with its first successful nuclear test. “Hurricane” as the weapon was known, was a plutonium bomb detonated near islands off the coast of Australia, and had a yield equivalent to 25 kilotons of TNT. Investigation and research into more complex weapons continued, and in 1958 Britain’s first Hydrogen Bomb was successfully tested. Also in 1958 the Atomic Energy Act was revised to allow closer cooperation between British and American atomic scientists.

During the Cold War, Britain had several hundred nuclear weapons available for delivery via aircraft. Small caches of bombs were placed in key areas around the globe to defend allies. Britain’s nuclear force was employed for defense of NATO, but also to protect the United Kingdom itself in the case of a national emergency. In 1968 Britain diversified its deterrent, deploying its first Polaris submarines with the help of the United States. In 1994 the first Vanguard class Trident submarine became operational, and all of the Polaris’ subs were eventually taken out of service by 1996.

The Strategic Defense Review (SDR) of March 1998 mandated major changes in Britain’s nuclear posture. It removed the last of the air-delivered nuclear bombs from service (they were completely dismantled by the end of August), leaving the Trident submarines as Britain’s sole deterrent force and its only nuclear weapon system. Only one submarine would be on patrol at a time, at a reduced state of alert, and the number of warheads was reduced. In addition, the report called for “a stockpile of fewer than 200 operationally available warheads.”

Britain’s Trident II missiles are stored among a larger pool of United States missiles in King’s Bay, Georgia. The Royal Navy retrieves missiles there and mates them to warheads onboard, returning missiles to the United States for servicing. There are no real differences between a United States Trident warhead and a British one. Britain has made modifications to give its Trident force a role in “sub-strategic deterrence” – some missiles are equipped with only one warhead while others have several, and each warhead has a variable yield: 0.3kt, 5-10kt, or 100kt. This allows the submarine force—at least in theory—to use a tactical strike to signal Britain’s intent to defend itself without becoming involved in a full-scale war.

Britain appears fairly comfortable with its nuclear deterrent force and strategy, and plans to keep these stable for the near future.


French and British Nuclear Forces, “NRDC Nuclear Notebook,” in Bulletin of Atomic Scientists September/October 2000.

Center for Defense Information – United Kingdom Nuclear Arsenal

Declared Nuclear States – Britain, from Nuclear Weapons Frequently Asked Questions, by Carey Sublette

United Kingdom Nuclear Forces Guide, Federation of American Scientists

Strategic Defence Review, Factsheet 22. Nuclear Deterrent

Britain’s Nuclear Weapons, High Energy Weapons Archive

“Where Her Majesty’s Weapons Were,” Bulletin of Atomic Scientists January/February 2001