Trident is Britain’s nuclear weapons system. It is made up of four nuclear submarines. Each sub carries up to 8 missiles on board, and each missile carries up to 5 nuclear bombs (warheads) on top. Each of these bombs is around eight times as destructive as the bomb which flattened Hiroshima in 1945, killing over 140,000 civilians. One Trident submarine patrols the seas at all times.