Comprehensive Test Ban Treaty

On September 22, 1979, a U.S. satellite detected a nuclear flash near the Prince Edward Islands off Antarctica. Called the Vela Incident [1], none of the existing nuclear powers took responsibility for it, which troubled the world's powers. It was later determind to be a test conducted by Israel and South Africa.

Since then, the world has been working towards a Comprehensive Test Ban Treaty to put an end to the testing of nuclear weapons. It started in 1963 with the Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water [2]. This treaty still allowed underground testing.

Further negotiations occurred, and in 1986 the Treaty on the Non-Proliferation of Nuclear Weapons [3] was accepted. In 1974, the Treaty on the Limitation of Underground Nuclear Weapon Tests [4], primarily between the U.S. and the Soviet Union, limited the yield of undeground nuclear detonations.

On September 10, 1996, the Comprehensive Nuclear-Test-Ban Treaty (CTBT) was adopted by the United Nations General Assembly. The CTBT has been signed by 185 countries (except for India) but only 170 countries have ratified it.

The treaty cannot go into effect until it is ratified by the governments of the nuclear powers. This table shows the nuclear powers and whether and when they've ratified it.

Many of the nuclear powers will not ratify it until they see that the other nuclear powers are willing to ratify it, primarily the United States. What's the holdup on the U.S. Congress ratifying the treaty?

The Brookings Institute reports [7] that it's Congressional Republicans who don't want a test ban and refuse to allow the Senate to ratify it. One of their principle concerns is that countries could cheat.

Monitoring cheating

Once all the nuclear powers ratify the CTBT treaty, the International Comprehensive Test Ban Treaty Organization (CTBTO) will monitor compliance. The CTBTO has already established a global monitoring network, called the International Monitoring System (IMS), that can detect nuclear weapons detonations anywhere on the planet. The IMS detects cheating, and has already proved its ability to do that by detecting North Korea's testing.

34 Republican Senators have threaten to defund the IMS, even though it addresses their concern about cheating. Defunding it allows cheating. Since defunding the IMS doesn't make sense, the Senate Republicans have some other reason for not wanting a comprehensive test ban.

You can get more details about treaty ratification at the Nuclear Threat Initiative website

References