Operation Hurricane was the first test of a British atomic device, detonated on 3 October 1952 in the lagoon in the Montebello IslandsinWestern Australia. During the Second World War, Britain commenced a nuclear weapons project, known as Tube Alloys, but the 1943 Quebec Agreement merged it with the American Manhattan Project. Several key British scientists worked on the Manhattan Project, but after the war the Americans ended cooperation. In January 1947, a cabinet sub-committee decided to resume efforts to build nuclear weapons. To test the effects of a ship-smuggled atomic bomb on a port (a threat of concern to the British at the time), the bomb was exploded inside the hull of a frigate, HMS Plym, leaving a saucer-shaped crater on the seabed 6 metres (20 ft) deep and 300 metres (1000 ft) across. With the success of Operation Hurricane, Britain became the third nuclear power, after the United States and the Soviet Union. (This article is part of a featured topic: Nuclear weapons and the United Kingdom.)