The British government did not seriously consider using its nuclear weapons against Argentina during the 1982 Falklands War. The United Kingdom had ratified the Treaty of Tlatelolco which established a nuclear-weapon-free zone across Latin America in 1969 and made a commitment in the United Nations during 1978 not to use these weapons against non–nuclear powers. The strong international norms against the use of nuclear weapons also influenced British decision making. The British War Cabinet never contemplated the use of nuclear weapons but the Prime Minister, Margaret Thatcher, may have done so separately when considering how she would respond to a serious defeat.

Four of the British Royal Navy warships which were sent to the South Atlantic following the invasion of the Falklands initially carried a total of thirty nuclear depth bombs as part of their standard armament. The Chief of the Defence Staff, Admiral Sir Terence Lewin, wanted to retain them on the ships in case the Soviet Union became involved in the war but this was opposed by civilian Ministry of Defence staff. The War Cabinet decided on 8 April 1982 to have these weapons removed but reluctantly reversed this decision three days later due to the impracticality of offloading the depth bombs at that time. On 28 May, the War Cabinet decided that the weapons should be returned to the UK and many of them were shipped back before the end of the conflict. The presence of nuclear depth bombs in the naval task force was reported by journalists soon after the end of the war but not confirmed by the British government until 2003.

It was alleged during and after the war that the British ballistic missile submarine had been sent to the South Atlantic. This has been denied by senior British government figures as well as Resolutions commanding officer. Historians have found no evidence of such a deployment. Nuclear-capable Avro Vulcan bombers were used in the war but were armed only with conventional bombs.

The British nuclear arsenal did not deter Argentina's invasion of the Falklands on 2 April 1982 as the Argentine government believed that the weapons would not be used. The Argentine government was unconcerned about the deployment of nuclear-capable British forces during the war. Experts have debated the implications of the war on whether nuclear deterrence prevents conflicts.

Background

Falklands War

The Falkland Islands is an archipelago in the South Atlantic Ocean and a British Overseas Territory. The islands are located from the UK. Sovereignty over the Falklands has been disputed between Argentina and the UK since 1833. A crisis over the islands developed in early 1982. On 2 April that year, Argentine forces invaded and captured the Falklands. At this time they were defended only by a group of 70 Royal Marines and Royal Navy personnel. The British government decided to retake the Falklands and very rapidly assembled and dispatched a task force of Royal Navy warships to begin this process. The military campaign was very risky for the British as the forces which could be deployed to the South Atlantic were not significantly superior to the Argentine defenders and it was difficult to sustain them at such a distance from the UK.

After initial diplomatic negotiations failed, fighting began on 1 May. Further negotiations proved fruitless, and British forces landed on the islands on 21 May. Following a series of fierce battles the Argentine forces there were defeated and surrendered on 14 June 1982. Several Royal Navy warships were sunk by Argentine air attacks during the war.

British nuclear weapons

The United Kingdom first tested a nuclear weapon in 1952 and began producing operational nuclear bombs from 1953. This made the UK the third country after the United States and Soviet Union to deploy these weapons. During the Cold War the British military was equipped with hundreds of nuclear devices. The size of the British nuclear arsenal peaked between 1974 and 1981 when it comprised approximately 500 nuclear warheads.

The British Armed Forces operated several types of nuclear weapons in 1982. A total of 100 warheads fitted to standard Polaris missiles and 35 fitted to missiles that had been upgraded through the Chevaline programme were carried by the Royal Navy's four ballistic missile submarines. The submarines comprised the British strategic nuclear force and were focused on deterring the Soviet Union. The Royal Navy was also assigned 43 WE.177A nuclear depth bombs; these were tactical nuclear weapons intended to be used against submarines. The Royal Air Force had 250 WE.177 bombs. In addition, the British Armed Forces had access to more than 150 nuclear warheads provided by the United States. Most of the American-owned warheads were assigned to the British Army of the Rhine that was stationed in Germany.

During the early 1980s many Royal Navy warships routinely carried WE.177A nuclear depth bombs. This practice had begun during the 1960s. The weapons had an explosive yield of and could be dropped from anti-submarine helicopters or Sea Harrier jet fighters. The Royal Navy considered the existence of the WE.177A nuclear depth bombs to be a sensitive issue and they were first officially disclosed as part of the 1981 Defence White Paper. The Navy had a policy of never confirming or denying whether specific ships were carrying nuclear weapons. The British Ministry of Defence had also never publicly commented on the whereabouts of nuclear weapons.

Nuclear weapons policies

Pre-war In 1967 the British government signed the Treaty of Tlatelolco which established a nuclear-weapon-free zone across Latin America and the nearby waters, including the Falkland Islands. The government ratified the treaty in 1969. Argentina also signed the Treaty of Tlatelolco in 1967 but had still not ratified it at the time of the Falklands War. Under the terms of the treaty, the UK was not able to use nuclear weapons against countries who had ratified the treaty. It also could not station these weapons in the Falkland Islands and its other dependencies in the South Atlantic or their territorial waters. Deploying nuclear weapons to other locations in the South Atlantic Ocean was not prohibited. Nuclear-powered ships, such as the Royal Navy's nuclear submarines, were outside the scope of the Treaty of Tlatelolco.

Prior to the Falklands War the British government had also provided a commitment not to use its nuclear weapons against countries that did not possess these weapons. In June 1978 the British government issued a "Negative Security Assurance" as part of a process overseen by the United Nations' Special Session on Disarmament. In this assurance the government stated that it would not use nuclear weapons against non–nuclear states unless any of these states attacked the "UK, its dependent territories, its armed forces or its allies" in "association or alliance with a nuclear weapons state". Argentina was a non–nuclear state at the time of the Falklands War. As the country had not ratified the Treaty on the Non-Proliferation of Nuclear Weapons or the Treaty of Tlatelolco the British were not legally obliged to treat it as such.

The Argentine government knew that it was not protected from British nuclear attack under the terms of the Treaty of Tlatelolco. However, it believed that these weapons would not be used in response to an invasion of the Falklands. This was because there was a strong international norm against the use of nuclear weapons as a result of their devastating effects – often labelled the "nuclear taboo". The national security experts John Arquilla and María Moyano Rasmussen have observed that due to the "normative inhibitions against the threat" of using nuclear weapons "there is no evidence of the [Argentine] junta being intimidated" by the British nuclear arsenal. The Argentine government decided to invade as it believed that the British government was not strongly committed to retaining the Falklands and could not deploy sufficient conventional forces to recapture the islands at such a distance from the UK.

During the war

From the outset of the conflict the British government had no intention of using nuclear weapons. On 27 April Viscount Trenchard, the Minister for Defence Procurement, stated in the House of Lords that "categorically ... there is no question at all of our using nuclear weapons in this dispute". This statement was made to ensure that the British government's position on the matter was clear. An opinion poll conducted in the UK on 14 April 1982 found that 93 per cent of respondents opposed using nuclear weapons against Argentina and 5 per cent supported doing so. A key issue underpinning the government's and public's views was a perception that the use of these extremely powerful weapons would have been grossly disproportionate to the threat Argentina posed to the UK.

The British official historian of the Falklands War, Sir Lawrence Freedman, investigated post-war "suggestions ... that the nuclear option had been seriously considered" as part of preparing the official history during the early 2000s. He found that the possibility of using nuclear weapons may have been included in a very early draft of the options paper prepared for the British government following the Argentine invasion, but this had been removed well before the paper was completed and submitted to ministers. Freedman concluded that "I have found no references to any consideration of nuclear employment. This was never taken seriously as a realistic possibility". This finding is in line with comments made by the Chief of the Defence Staff during the Falklands War, Admiral Sir Terence Lewin, who had told Freedman in 1989 that "there was never any thought whatever of giving advice to the War Cabinet that nuclear weapons should be used. It never entered our remotest thoughts".

During the mid-2010s historians Peter Hennessy and James Jinks also looked into the claims that the British government had been willing to use nuclear weapons against Argentina. While endorsing Freedman's conclusion that the War Cabinet did not consider the use of nuclear weapons, they stated that the Prime Minister, Margaret Thatcher, had probably done so separately. Hennessy and Jinks' source was the former Permanent Secretary of the Ministry of Defence, Sir Michael Quinlan, who had stated in a 2013 BBC interview that Thatcher told him after the war that she would have considered using nuclear weapons had the British forces faced defeat.

The political scientists Todd S. Sechser and Matthew Fuhrmann considered this issue in 2017. They believe that the British government deliberately deployed nuclear-capable forces to suggest to the Argentines that these weapons could be used, though no preparations to do so occurred. They labelled Quinlan's comments about Thatcher "a stunning revelation".

Nuclear depth bombs

Deployment

The Royal Navy hurriedly assembled a force of warships in response to the Argentine invasion of the Falklands. It comprised ships stationed in the UK and some that were on exercises or operational deployments elsewhere. It prioritised preparation of the task force as quickly as possible so that it could limit the build-up of Argentine forces on the islands, leading to urgent efforts at the Royal Navy's bases in the UK and Gibraltar to stock the ships with supplies and dispatch them.