In the 1980s, CND underwent a major revival in response to the resurgence of the Cold War. There was increasing tension between the superpowers following the deployment of SS20s in the Soviet Bloc countries, American Pershing missiles in Western Europe, and Britain's replacement of the Polaris armed submarine fleet with Trident missiles.
CND's membership increased rapidly, and in the early 1980s it claimed 90,000 national members and a further 250,000 in local branches. This made it one of the largest political organisations in Britain and probably the largest peace movement in the world (outside the state-sponsored movements of the Communist bloc). Public support for unilateralism reached its highest level since the 1960s. In October 1981, 250,000 people joined an anti-nuclear demonstration in London. CND's demonstration on the eve of Cruise missile deployment in October 1983 was one of the largest in British history, with 300,000 taking part in London as three million protested across Europe.