Page 1: 1963-77
Limits on Nuclear Testing
and the Treaty on the Non-Proliferation of Nuclear Weapons

1963: Partial Test Ban Treaty (PTBT)

President Kennedy ratifies the PTBT, 7 October 1963.

In the years leading up to the Cuban Missile Crisis, both the United States and the Soviet Union had put forth test ban proposals. But neither was ready for such a comprehensive ban. The US Atomic Energy Commission argued against a test ban along with the Department of Defense and the Joint Chiefs of Staff. Critics of a test ban downplayed the health effects of radioactive fallout from atmospheric tests while also arguing a test ban would impinge upon US national security interests. In the Soviet Union, opponents insisted that if inspections were part of the verification mechanism, the west would use these measures to gather intelligence. However, there was mounting public pressure both domestically and in the international arena against nuclear testing due to increased awareness of the implications for health, the environment and global security, as well as concern over the escalating nuclear arms race. 

This was the first time the world witnessed real progress on a test ban. Nevertheless nuclear weapons testing not only continued, albeit underground, but also increased greatly in numbers.
Shallow underwater nuclear test "Baker", part of Operation Crossroads, Bikini Atoll, 25 July 1946

With no resolution over the OSI issue and the number of seismic stations necessary to verify compliance with a comprehensive test ban, negotiations began on a Partial Test Ban Treaty (PTBT). Signed by the United Kingdom, the United States and the Soviet Union on 5 August 1963, the PTBT banned nuclear testing in the atmosphere, underwater and in space. It entered into force on 10 October 1963. The treaty stipulated that signatory-states could not “carry out any nuclear weapon explosion, or any other nuclear explosion…in the atmosphere; beyond its limits, including outer space; or under water, including territorial waters or high seas”. This treaty also included peaceful nuclear explosions (PNEs). In terms of the effects on health and the environment, PNEs were qualitatively no different from weapons tests.

The signing of the PTBT amounted to nothing less than a historic milestone in arms control. This was the first time the world witnessed real progress on a test ban between the great powers struggling for military and geopolitical superiority in the Cold War. Nevertheless, although a necessary step towards a comprehensive test ban treaty, the fundamental role of the PTBT was to address environmental issues rather than disarmament. Nuclear weapon testing not only continued, albeit underground, but also increased greatly in number through the better part of second half of the twentieth century.  Moreover, on 16 October 1964, China became the fifth country in the world to test a nuclear weapon. It is also important to note that China and France did not sign the PTBT and carried out atmospheric testing until 1980 and 1974 respectively. View a visual overview of worldwide atmospheric and underground testing.