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Evolution of the Comprehensive Test Ban Treaty

The purposes and objectives of a test ban have evolved significantly over the treaty's 40-year negotiating history. Originally envisioned as a way to stop the arms race and limit environmental contamination, by 1996 the Comprehensive Test Ban Treaty was motivated primarily out of concern about the spread of nuclear weapons to other nations.

First Goals: Stop the Arms Race and Protect the Environment

Prime Minister Nehru of India was the first to propose a ban on nuclear testing. His proposal came in 1954, shortly after the US Bravo test in the Pacific. A 15-megaton surface test at Bikini Atoll resulted in radioactive fallout reaching a Japanese fishing boat (the "Lucky Dragon"), killing one crew member and injuring others.

This event sparked international interest in a test ban for both environmental and national security reasons. First, a ban on testing would prevent atmospheric contamination like the Lucky Dragon incident. Second, a test ban in 1954 would have halted the continued development of nuclear weapons. At that time the United States was just beginning to refine thermonuclear (two-stage) weapons, and a test ban would have severely restricted this effort. The development of smaller, more powerful warheads led to the introduction of ballistic missiles as a nuclear delivery system, and eventually missiles with multiple, independently-targetable reentry vehicles (MIRVs). A test ban would not have stopped the development of ballistic missiles, but without the warheads to go on top missile development would have had less impetus. Missiles soon displaced strategic bombers as the primary means for delivering US nuclear weapons.

In 1954 there were three nuclear weapon states: the United States, the Soviet Union, and Britain. France joined the group in 1960; China in 1964. Experts believe that Israel has had a nuclear weapons capability since the 1970s. India conducted a nuclear test in 1974 for supposedly "peaceful" purposes. (In 1998, both India and Pakistan tested nuclear devices and subsequently declared themselves nuclear weapons states.) And South Africa developed nuclear bombs in the 1980s (but dismantled its six bombs in 1991). These additions to the number of nuclear-capable nations gave new impetus to a test ban -- to stop the spread of nuclear weapons to more nations or groups.

In response to public concern about radioactive contamination in the United States, and a general sense in both the United States and the Soviet Union that restraint was called for after the 1962 Cuban missile crisis, in 1963 the United States, the Soviet Union, and Britain signed the Partial Test Ban Treaty. This treaty banned nuclear testing in the atmosphere, in space, and under water. By removing the mushroom cloud from modern experience, the treaty addressed the most prominent environmental concerns about nuclear testing in the United States. But nuclear tests did not stop: they moved underground. In addition, France continued atmospheric tests until 1974; China until 1980.

Second Goals: Arms Control and Nonproliferation

After the Partial Test Ban Treaty, the main purposes for a test ban became arms control and nonproliferation. But instead of pursuing these goals through a comprehensive test ban, other treaties were negotiated. In 1970, the Nuclear Non-Proliferation Treaty was signed to limit the spread of nuclear weapons, with an initial duration of 25 years. Its preamble calls for the conclusion of a comprehensive test ban. But it was not until efforts to extend the Non-Proliferation Treaty got under way that a comprehensive test ban received the serious consideration necessary to produce an agreed treaty text. At the same time, arms control issues were dealt with through the SALT (Strategic Arms Limitation Talks) and START treaties.

Other than limiting the yield of nuclear tests to 150 kilotons under the 1974 Threshold Test Ban Treaty and the 1976 Peaceful Nuclear Explosions Treaty, the United States and the Soviet Union did not reach formal agreements on nuclear testing until nuclear proliferation became a more widespread concern in the 1990s. The end of the Cold War led the United States to cancel orders for new warheads, thereby essentially ending the arms race. This removed the central argument against a comprehensive test ban, as new types of weapons were no longer needed. But other arguments for continued testing, such as maintaining warhead safety and reliability, and the difficulty of verifying a ban on underground tests, slowed treaty efforts.

In the 1990s, the necessity of a comprehensive test ban to address proliferation became clear. Revelations of a nuclear arsenal in South Africa, a serious attempt by Iraq to build such an arsenal, and continuing efforts by other nations focused international attention on the 1995 conference to extend the Nuclear Non-Proliferation Treaty. The nuclear states pushed strongly for indefinite extension, but a number of nonaligned nations resisted. Their central argument was that the nuclear states had not delivered on their disarmament obligations under the Nuclear Non-Proliferation Treaty, and thus they did not deserve indefinite extension. To bring these nations along, the nuclear states agreed to a number of disarmament steps, foremost among them to conclude a comprehensive test ban by 1996. The Comprehensive Test Ban Treaty was finally signed in September of that year.

As of the end of 1999, 23 of the 44 nations required to put the treaty into force have ratified the treaty. India, Pakistan, and North Korea are the only nations among the 44 that have yet to sign the treaty. The United Kingdom and France, both declared nuclear powers, have ratified the treaty. Despite the US Senate's 1999 rejection of the treaty, Russia and China have both declared their intention to ratify it.


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