A nuclear-free zone is a region or area in which the manufacture, testing, and deployment of nuclear weapons is banned. Nuclear powers outside the zone are banned from testing, deployment, and use of nuclear weapons inside the zone.
Nuclear-free zones are established by treaty. The first one was in the Antarctic in 1959. Treaties covering regions without residents were signed to cover space in 1967 and the ocean bottom in 1971. The first treaty covering a region inhabited by human beings was the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (Treaty of Tlatelolco) in 1967. This effort to remove the nuclear menace from Central and South America was spurred by the Cuban Missile crisis. In 1985 various nations around the Pacific Rim signed the South Pacific Nuclear Free Zone Treaty (Treaty of Rarotonga).
The end of the Cold War helped spread movements to expand nuclear-free zones, and the Treaty on the Southeast Asia Nuclear Weapon-free Zone was signed in 1995. The Africa Nuclear-Weapon-Free Zone Treaty (Treaty of Pelindaba) was signed in 1996. With the addition of these, virtually the entire southern hemisphere became a nuclear-free zone.
To give these treaties meaning, not only the countries in the region concerned but the nuclear powers must sign and abide by them.

Expanding Nuciear-free Zones
1 Antarctic Treaty igned in December 1959 Forty-two nations signed and ratified the treaty which banned all nuclear explosions and disposal of radioactive wastes in all areas south of the 60th parallel. The five nuclear powers signed and ratified the protocol.
2 Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean
(Treaty of Tlatelolco)
signed February 1967 All the 33 nations within the sphere of application signed the treaty (32 of these also ratified it). The five nuclear powers signed and ratified the protocol.
3 South Pacific Nuclear-Free Zone Treaty
(Treaty of Rarotonga)
signed in August 1985 Of the 14 countries and two regions that are members of the inter-governmental organization South Pacific Forum (SPF), which is comprised of Australia, New Zealand, and island regions, 11 countries and both regions signed. (Of these, 10 countries and the two regions ratified the treaty.) The five nuclear powers signed the protocol.
4 Treaty on the Southeast Asia Nuclear Weapon-free Zone signed in December 1995 The ten countries of ASEAN (Association of Southeast Asian Nations) signed the treaty. (Of these, eight ratified.) None of the five nuclear powers signed the protocol.
5 Africa Nuclear-Weapon-Free Zone Treaty
(Treaty of Pelindaba)
signed in April 1996 Of the 53 member nations of the Organization of African Unity (OAU), 49 signed the treaty. (Of these, two ratified the treaty.) The five nuclear powers signed the protocol.