In 1993, South Africa
became the first country to scrap nuclear weapons.
In 1995, after the collapse of the Soviet Union, Belarus, Kazakhstan and Ukraine acceded to the NPT and returned all nuclear weapons stationed on their soil to Russia.
Algeria built up its nuclear infrastructure during the 1980s and is believed to have conducted research into nuclear weapons. It agreed to IAEA safeguards in 1992, and joined the NPT in 1995.
In competition with one another, Argentina and Brazil made major efforts to build nuclear weapons in the 1970s and 80s, but their programmes are now considered dormant. Both are NPT members and have signed bilateral agreements on mutual supervision of nuclear facilities and materials.
Germany and Japan attempted to build nuclear weapons during World War II, though neither gave them high priority. Both are now NPT members.
Iraq began a nuclear programme in the 1970s, but this was ended after an Israeli air raid in 1981, the 1991 Gulf War, and years of sanctions.
Libya had a secret nuclear development programme based on designs by the Pakistani scientist AQ Khan. This programme was uncovered during investigations into Khan and in 2003, Libya admitted it, abandoned its plans and was brought under full inspection.
Sweden and Switzerland conducted detailed research into nuclear weapons in the 1950s and 60s, before both decided against building them.
Taiwan, although not recognized by the UN as a state, began research into nuclear weapons after China's first atomic test in 1964. It regards itself as part of the NPT.
As of 2000, 187 countries have signed the NPT. Most major industrialised powers outside the categories listed in this guide have the technical skills and resources to build a bomb. Many have civilian nuclear programmes and some have carried out research into nuclear weapons, at some time or another, though none are considered to have serious inclinations towards actually building or acquiring them.