Nuclear weapons were developed towards the end of the Second World War. The two atomic bombs dropped on Japan, at Hiroshima and Nagasaki, demonstrated their huge destructive potential and they were credited with bringing the war to an end. Russia and America built up huge stockpiles of these weapons, which have become increasingly powerful, in an arms race during the Cold War period.
The logic behind this arms race was to deter the opponent from attacking, because there would be instant retaliation and both countries would be completely destroyed: the doctrine of ‘mutually-assured destruction’. The whole point of having these nuclear weapons was that no one would dare to use them. It was obvious, though, that the situation would become increasingly risky if many other countries possessed nuclear weapons.
The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) of 1968 was intended to restrict nuclear weapons to the five nuclear powers which then had them; these nuclear powers undertook to negotiate to achieve complete disarmament; the non-nuclear signatories to the treaty would submit to inspections to prevent proliferation. This was very effective during the Cold War period but the treaty began to unravel towards the end of the century:
- The nuclear powers didn’t scale down their arsenals.
- Israel, India, Pakistan and North Koreaall made nuclear weapons.
It has been argued that this happened at least partly because the nuclear powers made insufficient progress towards disarmament, but for whatever reason the treaty now appears to have crumbled completely. And a world in which many countries have nuclear weapons is vulnerable to mistakes being made and to weapons falling into the hands of people who would use them without qualms. It is now debatable whether disarmament can ever be confidently achieved, but some new arrangements need to be negotiated to reduce what otherwise looks like an exponentially increasing risk.
The proliferation of nuclear weapons is increasingly threatening world peace.
 The BBC published an article on 15 February 2012, entitled How did we forget about mutually-assured destruction? It reviewed the history of the doctrine and asked why people are less aware of the risks today. The article was available in April 2018 at http://www.bbc.co.uk/news/magazine-17026538.
 In a meeting hosted on 17 September 2007 by the Carnegie Endowment for International Peace, entitled After Iraq: U.S. Strategy in the Middle East after the Troops Come Home, Jessica Mathews argued that the Non-Proliferation Treaty was crumbling because of inadequate progress on nuclear disarmament. A transcript of the proceedings was available in April 2018 at http://www.carnegieendowment.org/files/after_iraq_transcript.pdf.