Nuclear disarmament refers to both the act of reducing or eliminating nuclear weapons and to the end state of a nuclear-weapon-free world, in which nuclear weapons are completely eliminated.Nuclear disarmament groups include the Campaign for Nuclear Disarmament, Peace Action, Greenpeace, International Physicians for the Prevention of Nuclear War, Mayors for Peace, Global Zero, the International Campaign to Abolish Nuclear Weapons, and the Nuclear Age Peace Foundation. There have been many large anti-nuclear demonstrations and protests. On June 12, 1982, one million people demonstrated in New York City's Central Park against nuclear weapons and for an end to the cold war arms race. It was the largest anti-nuclear protest and the largest political demonstration in American history.In recent years, some U.S. elder statesmen have also advocated nuclear disarmament. Sam Nunn, William Perry, Henry Kissinger, and George Shultz have called upon governments to embrace the vision of a world free of nuclear weapons, and in various oped columns have proposed an ambitious program of urgent steps to that end. The four have created the Nuclear Security Project to advance this agenda. Organisations such as Global Zero, an international non-partisan group of 300 world leaders dedicated to achieving nuclear disarmament, have also been established.Proponents of nuclear disarmament say that it would lessen the probability of nuclear war occurring, especially accidentally. Critics of nuclear disarmament say that it would undermine deterrence.