Collective opposition to war. The Western peace movements of the late 20th century can trace their origins to the pacifists of the 19th century and conscientious objectors during World War I (see pacifism). The campaigns after World War II have tended to concentrate on nuclear weapons, but there are numerous organizations devoted to peace, some wholly pacifist, some merely opposed to escalation.
Other organizations are concerned with the future of life on planet Earth and the environment. In the US, opposition to the Vietnam War, which grew from the late 1960s, was the primary post-World War II peace movement. It greatly influenced US politics and society, although Ban the Bomb opposition was older, a post-World War II posture against nuclear weapons.