World's arms-control efforts since '50s

1957: The International Atomic Energy Agency was set up to monitor the proliferation of nuclear technology, including nuclear weapons.

1968: The Nuclear Non-Proliferation Treaty was signed to prevent further spread of nuclear weapons technology to countries outside the five that possessed them: The United States, the Soviet Union, the United Kingdom, France and China.

1972: The SALT I (Strategic Arms Limitation Talks) between the United States and Soviet Union led to the Anti-Ballistic Missile Treaty, which sets limits on the anti-ballistic missile systems used in defending areas against missile-delivered nuclear weapons. It was in effect for the next 30 years until the US unilaterally withdrew from the deal in 2002.