The unexpected seizure of the Falkland Islands or Islas Malvinas in April 1982 by the Argentine junta led by Gen. Leopoldo Galtieri was a failure of intelligence brought about by the Secret Intelligence Service’s inability to collect intelligence in Buenos Aires and Argentine guile in not deploying troops monitored by GCHQ. In 1981 the Argentine government had misinterpreted the public announcement that the Royal Navy intended to withdraw HMS Endurance, GCHQ’s sole signals intelligence collection platform in the area, from the South Atlantic, and this led to the mistaken assessment that Great Britain would not fight to recover the disputed islands if there was an invasion. The junta also miscalculated that the United States would remain neutral in any conflict and that the Soviet Union would veto any resolution critical of Argentina.
During the conflict, which was never formally declared a war in order to avoid declarations of neutrality from strategically important countries in West Africa, the SIS conducted an effective operation to prevent Argentina from acquiring any further reloads of the lethal French-built Exocet missile, and GCHQ intercepted enemy wireless traffic which disclosed the exact location and strength of the occupation forces. A landing by British troops, followed by a swift advance to the capital, Port Stanley, resulted in a humiliating surrender of the garrison, which—following the loss of the cruiser General Belgrano, sunk by the nuclear submarine HMS Conqueror—was isolated from the mainland and supported only by Argentine aircraft.
Following the liberation of the Falklands, a committee of inquiry headed by Lord Franks investigated the failure of intelligence, and the British government’s lack of advance notice of Argentine aggression, but only part of the final report was published.
The prosecution of the war was studied with interest by military analysts, as it was the first occasion in which a surface vessel had been sunk by a nuclear submarine (except in practice on exercise), the first time the Royal Navy had engaged an enemy since the Korean War, and the first time a nuclear submarine had been bombed
(albeit accidentally by returning Argentine aircraft jettisoning ordnance before landing) by aircraft. The loss of HMS Sheffield to a debilitating internal fire carried by cable ducts following an Exocet missile attack prompted a redesign of wiring aboard all naval vessels.