Nuclear disarmament

Nuclear disarmament refers to the efforts of political movements and states to reduce or eliminate nuclear weapons with the goal of achieving a world free of nuclear weapons. Whether this is possible given the apparent utility of nuclear weapons for (hypothesized) deterrence or if it would affect the likelihood of war waged with other weapons is unclear. In any case, most countries that currently have nuclear weapons aren't going to give them up any time soon.

After the fall of the USSR, the republics of Belarus, Ukraine and Kazakhstan surrendered the Soviet nuclear weapons stationed on their territory to Russia in exchange for promises that Russia (and others) would respect their borders, which is part of why Russia's conquest "protection" of Crimea is such a problem. Many nonproliferation and disarmament treaties have been signed as well, which have helped the cause to some extent. However, the only country that has ever fully dismantled its nuclear arsenal is South Africa. In some cases, countries that were in varying degrees of closeness to achieving nuclear capability abandoned their nuclear projects or at least its military aspect. One example of this is Germany, that never resumed its wartime research into nuclear weapons. Brazil similarly got rid of its nuclear arms project when the regime changed from authoritarian to democratic.

Peace Symbol
The original meaning of the Peace Symbol was a combination of the semaphore letters N and D, for "Nuclear Disarmament". But of course, the symbol took on more meaning as time went on.