Hard Rock (sometimes Operation Hard Rock or the Hard Rock exercise) was a British civil defence exercise planned by the Conservative government to take place in September–October 1982. One of a series of regular national civil defence exercises, it followed Square Leg in 1980. As the public reaction to the scale of devastation forecast in Square Leg was poor, the planner deliberately scaled down the number of warheads supposed for Hard Rock. Despite this, the Campaign for Nuclear Disarmament (CND), who opposed nuclear warfare and were against civil defence exercises, suggested that such an attack as Hard Rock anticipated would have led to the deaths of 12.5 million people.
Since 1980, many British local authorities, who played key roles in civil defence planning, had become nuclear-free zones, opposed to nuclear weapons and nuclear power. Many of these authorities refused to take part in Hard Rock, although finance and the unofficial policy of the Labour Party also played a part. By July, twenty local authorities, all Labour-run, had indicated their refusal to take part and seven more would take part in only a limited manner. Hard Rock was postponed indefinitely, effectively cancelled. In response, the government passed the Civil Defence (General Local Authority Functions) Regulations 1983, compelling local authorities to take part in civil defence exercises.