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Limits on Nuclear Testing and the Treaty on
the Non-Proliferation of Nuclear Weapons

1967: Outer Space Treaty

The United Nations General Assembly adopted the Outer Space Treaty in resolution 2222, 10 October 1967.

Following consideration by the Legal Subcommittee in 1966, the United Nations General Assembly adopted the Outer Space Treaty in resolution 2222. The Outer Space Treaty, also known as the Treaty on Principles Governing the Activities of States in the Exploration and use of Outer Space, including the Moon and other Celestial Bodies, prohibits States Parties from placing in orbit around the earth any objects carrying nuclear weapons or other weapons of mass destruction. In addition to prohibiting nuclear testing in space, the Outer Space Treaty also prohibits Parties from engaging in military maneuvers on celestial bodies, conducting nuclear tests on celestial bodies, installing weapons systems or constructing military bases on celestial bodies.

1967: The Treaty of Tlatelolco

The world’s first Nuclear-Weapon-Free Zone was created by the countries of Latin America and the Caribbean in 1967. The Parties to the Treaty of Tlatelolco committed themselves not to manufacture, acquire, test or possess nuclear weapons.

As the Cold War intensified and both the United States and the Soviet Union increased nuclear testing underground in both quantity and yield, the international community together with movements in civil society sought to constrain the spread of nuclear weapons.

1968: Treaty on the Non-Proliferation of Nuclear Weapons (NPT)

US Army troops attack towards an atomic blast during a maneuver, part of operation Tumbler-Snapper, at Nevada Proving Grounds, 1 June 1952. As the Cold War intensified, both the United States and the Soviet Union increased nuclear testing underground in both quantity and yield.

As early as 1959, the United Nations General Assembly adopted a resolution put forth by Ireland calling for nuclear weapon States (NWS) to refrain from transferring nuclear weapons to non-nuclear weapon States (NNWS). As the Cold War intensified and both the United States and the Soviet Union increased nuclear testing underground in both quantity and yield, the international community together with movements in civil society sought to constrain the spread of nuclear weapons. Many observers believed that due to the strategic superiority granted by the atomic bomb, the proliferation of nuclear weapons was inevitable. President Kennedy famously predicted that by the mid-seventies, 15-20 States in the world would possess nuclear weapons.

Underground salt dome cavity produced by the U.S. nuclear test "Gnome", part of Operation Nougat, 10 December 1961. In 1965, the Soviet Union maintained that national detection systems should remain the only means with which to monitor underground nuclear tests.

In 1965, although the United States proposed the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), certain states argued that a comprehensive nuclear test ban would cover all related aspects of nuclear nonproliferation. The United States continued to push for an NPT and proposed a revision of the PTBT to include a verifiable underground test ban. However, it was certain the Soviet Union would not agree to the verification measures proposed by the United States that included monitoring systems and on-site inspections. The Soviet Union maintained that national detection systems should remain the only means with which to monitor underground nuclear tests. During a meeting of the ENDC, Sweden attempted to resolve the issue by proposing “challenge inspections” whereby states unable to produce satisfactory explanations of suspicious events were subjected to challenge inspections.