Looking back on 65 years of nuclear non-proliferation efforts

From the moment that their enormous destructive capacity was first shown to the world, when used by the United States to bomb the Japanese cities of Hiroshima and Nagasaki in August 1945, nuclear weapons have been universally considered to be the cruellest weapons that exist. When used, nuclear weapons kill large numbers of non-belligerents immediately and cause a great deal of long-term harm to people and the environment by their radiation effects.

Although the unprecedented cruelty of nuclear warfare resulted in a global aversion to these weapons, several other countries also developed or tried to develop nuclear weapons after 1945. The weapons were also considerably improved — compared to modern atomic weapons like the hydrogen bomb, the ones that destroyed Hiroshima and Nagasaki had relatively little power. At the same time, much international efforts have been put into stopping the spread of nuclear weapons and, eventually, reaching complete nuclear disarmament. While the media are nowadays reporting on alarming topics like the (supposed) nuclear weapons programmes of Iran and North Korea, the tensions between the nuclear weapons possessor states India and Pakistan, and the (assumed) black market in nuclear materials in some former Soviet states, one could easily overlook these efforts. Looking retrospectively, how successful have the international nuclear non-proliferation efforts been in the last 65 years?