Limited Test Ban Treaty (1963)


Trilateral agreement negotiated by the US, USSR, and UK prohibiting tests of nuclear devices in the atmosphere, in outer space, and underwater. Allows nuclear testing to continue underground, so long as radioactive debris is not allowed "outside the territorial limits" of the testing state. The treaty has since been signed by a total of 116 countries, including potential nuclear states Argentina, Brazil, India, Israel, Pakistan, and South Africa. Though two major nuclear powers, France and the People's Republic of China, have not signed, they are now abiding by its provisions. In 1992, China exploded a bomb beyond the LTBT limits.


The Test Ban Treaty of 1963 prohibits nuclear weapons tests "or any other nuclear explosion" in the atmosphere, in outer space, and under water. While not banning tests underground, the Treaty does prohibit nuclear explosions in this environment if they cause "radioactive debris to be present outside the territorial limits of the State under whose jurisdiction or control" the explosions were conducted. In accepting limitations on testing, the nuclear powers accepted as a common goal "an end to the contamination of man's environment by radioactive substances."

Efforts to achieve a test ban agreement had extended over eight years. They involved complex technical problems of verification and the difficulties of reconciling deep-seated differences in approach to arms control and security. The uneven progress of the negotiations reflected, moreover, contemporaneous fluctuations in East-West political relationships.

Prior to SALT, no arms control measure since World War II had enlisted so intensely the sustained interest of the international community. The United States in November 1952, and the Soviet Union in August of the following year, exploded their first hydrogen devices, and rising concern about radioactive fallout and the prospect of even more powerful explosions spurred efforts to halt testing. Succeeding events gave the dangers of fallout concrete and human meaning. In March 1954 the United States exploded an experimental thermonuclear device at Bikini atoll, expected to have the power of eight million tons of TNT. The actual yield was almost double that predicted, about 15 megatons, and the area of dangerous fallout greatly exceeded original estimates. A Japanese fishing vessel, the Lucky Dragon , was accidentally contaminated, and its crew suffered from radiation sickness, as did the inhabitants of an atoll in the area. In another such accident, radioactive rain containing debris from a Soviet hydrogen bomb test fell on Japan.

As knowledge of the nature and effects of fallout increased, and as it became apparent that no region was untouched by radioactive debris, the issue of continued nuclear tests drew widened and intensified public attention. Apprehension was expressed about the possibility of a cumulative contamination of the environment and of resultant genetic damage.

Efforts to negotiate an international agreement to end nuclear tests began in the Subcommittee of Five (the United States, the United Kingdom, Canada, France, and the Soviet Union) of the U.N. Disarmament Commission in May 1955, when the Soviet Union included discontinuance of weapons tests in its proposals.

Public interest in the course of the negotiations was active and sustained. In individual statements and proposals, and in international meetings, governments pressed for discontinuance of nuclear tests. A dozen resolutions of the General Assembly addressed the issue, repeatedly urging conclusion of an agreement to ban tests under a system of international controls.

The three-power meetings began on July 15. The long years of discussion had clarified views and greatly reduced areas of disagreement, and a Treaty was negotiated within 10 days. It was initialed on July 25 and formally signed at Moscow on August 5, 1963, by U.S. Secretary of State Dean Rusk, the Foreign Minister of the USSR, Andrei Gromyko, and the Foreign Minister of the U.K., Lord Home. On September 24, after extensive hearings and almost three weeks of floor debate, the Senate consented to ratification of the Treaty by a vote of 80 to 19. It was ratified by President Kennedy on October 7, 1963, and entered into force on October 10 when the three original signatories deposited their instruments of ratification.

The parties to the Treaty undertake "not to carry out any nuclear weapon test explosion, or any other nuclear explosion," in the atmosphere, under water, or in outer space, or in any other environment if the explosion would cause radioactive debris to be present outside the borders of the state conducting the explosion. As explained by Acting Secretary of State Ball in a subsequent report to President Kennedy, "The phrase 'any other nuclear explosion' includes explosions for peaceful purposes. Such explosions are prohibited by the Treaty because of the difficulty of differentiating between weapon test explosions and peaceful explosions without additional controls."

The Treaty is of unlimited duration. Article II notes that any party may propose amendments, and that, if so requested by one-third or more of the states Party, the Depositary Governments are to convene a conference to consider the amendment. This article stipulates that any amendment must be approved by a majority of Parties, including the three Original Parties. Article III opens the Treaty to all states, and most of the countries of the world are parties to it. The Treaty has not been signed by France or by the Peoples Republic of China.

In August 1988, six countries (Mexico, Indonesia, Peru, Sri Lanka, Yugoslavia, and Venezuela) presented a proposal to the three Depositary Governments to amend the LTBT and to have a special amendment conference to consider this proposal. Their proposal was to extend the LTBTs prohibitions to all environments, transforming the LTBT into a comprehensive test ban. By late March 1989 the Depositary Governments had received the requisite number of requests, in accordance with Article II of the Treaty, to convene such a conference for consideration of the proposed amendment. The Conference was held in January 1991. The United States, strongly opposed to using the LTBT as a vehicle for negotiating a comprehensive test ban, made it clear to all participants that it would block any attempt to amend the LTBT by consensus.

Source: Department of State