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 HMS Resolution had been sent to the South Atlantic to potentially attack Argentina. This has been denied by senior British government figures as well as Resolution's 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.