The WE.177, originally styled as WE 177, and sometimes simply as WE177, was a series of tactical and strategic nuclear weapons with which the Royal Navy (RN) and the Royal Air Force (RAF) were equipped. It was the primary air-dropped nuclear weapon in the United Kingdom from the late 1960s into the 1990s. All versions could be delivered by fixed-wing aircraft and could be parachute retarded. The WE.177A, in anti-submarine mode, could also be carried by helicopters.