ARMS: Apart from the five permanent members of the UN Security Council (the US, Russia, China, France and Britain), which are all nuclear powers, around 25 other countries have sought to obtain nuclear weapons, say international analysts.
Israel has never officially declared itself a nuclear power but is by some distance the mightiest nuclear power outside the Big Five, with the first prime minister, David Ben-Gurion, inaugurating the project in the mid-1950s in great secrecy. India, Pakistan and South Africa are known to have succeeded, though South Africa voluntarily relinquished its bomb in the 1990s, a unique event.
North Korea is feared to be building a bomb while Saddam Hussein's Iraq tried and failed. A drip-feed of revelations from UN inspectors over recent months is hardening suspicions that Iran is bent on acquiring nuclear weapons, or creating the wherewithal.
Japan has the fissile material and the know-how to develop one quickly.
Other countries occasionally rumoured to have nuclear ambitions include Brazil, Argentina, Libya and Algeria.