The Comprehensive Nuclear Test Ban Treaty
August 26, 2009
Q1: How many nuclear weapon tests have been conducted?
A1: More than 2,000 nuclear tests have been carried out since 1945: more than 1,000 by the United States, more than 700 by the Soviet Union, 210 by France, 45 by the United Kingdom, 45 by China, 4 by India, 2 by Pakistan, and 2 by North Korea. The United States, Russia, and United Kingdom have maintained a moratorium on testing since 1992; China and France stopped testing during the negotiations on the Comprehensive Nuclear Test Ban Treaty (CTBT), which concluded in 1996.
Q2: Why is a treaty necessary?
A2: The treaty prohibits countries from carrying out nuclear weapon test explosions or any other nuclear weapon explosion. Most experts agree that a treaty will prevent countries from developing or improving nuclear weapons and thus impede a nuclear arms race, curb nuclear weapons proliferation, and strengthen the Nuclear Nonproliferation Treaty (NPT). The indefinite extension of the NPT in 1995 included the obligation to complete the Comprehensive Nuclear Test Ban Treaty, and the NPT Review Conference in 2000 included the agreement to achieve early entry into force of the CTBT.
Q3: What are the provisions for verification?
A3: The core of the verification regime is the International Monitoring System (IMS), which is composed of 321 stations in 92 different countries. It is a globally linked network that uses three acoustic waveform techniques to monitor underground with 170 seismic stations, the atmosphere with 60 infrasound stations, and underwater with 11 hydroacoustic stations. In addition, radionuclide techniques detect airborne radioactive particles and gases with 80 radionuclide stations and 16 radionuclide laboratories. The global communications infrastructure brings the data to the International Data Center in Vienna via state-of-the-art satellite and other communications systems. The Center analyzes the data and produces an integrated “event bulletin” based on the fusion of data from all technologies. These bulletins include some 100 earthquakes and as many mining and quarry events each day, as well as infrasound events such as bolides or strong weather systems and radioactive releases. The bulletins are routinely sent to States Signatories.
In the case of a suspected nuclear test, once the treaty enters into force it provides for a consultation and clarification procedure and, if that is not satisfactory, an on-site inspection. Many techniques may be used for an on-site inspection, ranging from overflights, local seismic networks, and ground-penetrating radar to drilling. Field exercises have been held at Semipalatinsk in Kazakhstan to test the technologies and equipment. At least 30 of the organization’s 51 members must vote for such an inspection, which may not exceed an area of 1,000 square kilometers.
Beyond the methods provided for in the treaty, States Parties may use national technical means. Satellites, high-resolution imagery, optical flash sensors, x-rays, and other techniques may be employed, along with the many thousands of seismic stations that are not a part of the IMS network.
Q4: When will it enter into force?
A4: The treaty will enter into force once 44 specified countries that have nuclear power reactors have ratified it. There are nine countries that have not done so: China, Egypt, India, Indonesia, Iran, Israel, North Korea, Pakistan, and the United States. Many believe that once the United States ratifies the treaty a number of others will follow. More than 180 states have signed, and 149 have ratified the treaty, including all those of the European Union and Russia.
Q5: Why has the United States not ratified the treaty?
A5: Although the U.S. Senate did not ratify the treaty when it was put to a vote in 1999, President Barack Obama recently stated that he would aggressively pursue ratification of the CTBT. The Department of State, the National Nuclear Security Administration, and the National Academy of Sciences have sponsored a project to review and update a 2002 report on technical issues related to the treaty. A recently concluded international scientific study found that the capabilities of the verification system are better than expected by those who designed it. The recent report of the Congressional Commission on the Strategic Posture of the United States did not reach a consensus view on the CTBT. Commissioners opposing the treaty believe that while the United States would not test a device that produces a nuclear yield, other countries with different interpretations of the treaty could conduct tests with hundreds of tons of nuclear yield, allowing them to develop or advance nuclear capabilities. The five nuclear-weapon states (P5) agreed to a zero yield treaty during the negotiations on the treaty, and such large tests would be detected by the IMS. However, critics believe that Russia and possibly China are carrying out low-yield tests; they believe that the United States could fall behind in its capability to deter tactical threats against allies. They believe that a zero-yield ban is unverifiable and that countries could conduct tests without being detected.
In addition, some believe that a CTBT would diminish the confidence in the reliability of the U.S. nuclear-weapons stockpile, thereby reducing the credibility of America’s nuclear deterrent. They also argue that the provisions for on-site inspection are too restrictive and that the absence of testing does not lead to nonproliferation.
Proponents of the treaty believe it will improve U.S. security and prevent the proliferation of nuclear weapons and their use. They believe that without a treaty other potential adversaries could develop and test new or enhanced weapons without limitations. Thus, nuclear programs of other countries could present a greater threat to the United States without a CTBT than with one, as potential violators could only obtain minimal value from a clandestine undetected test. In addition, the provision of on-site inspections would clarify suspicious events.
Advocates believe that the United States obtains enough information from past testing and the Stockpile Stewardship Program (which includes experimental, diagnostic, and computation tools) to maintain a reliable and secure nuclear weapons stockpile without further testing. The report described the role of nuclear weapons in U.S. policy, which does not envision new types of weapons that might require testing. Further, treaty supporters believe that a strong Stockpile Stewardship Program is essential and is able to maintain the safety and reliability of the warheads under a CTBT. If the United States found that it needed to test in order to maintain its warhead safety and reliability, it could withdraw from the treaty. However, the IMS complements the national monitoring capabilities with additional information, and the treaty creates a norm that would be difficult to break.
Jenifer Mackby is a fellow in the International Security Program at the Center for Strategic and International Studies in Washington, D.C.
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