Comprehensive Nuclear Test Ban Treaty
This year marks the 20th anniversary of the moratorium on nuclear testing by the United States and the Soviet Union. Following a combined total of 2,000 test explosions, only a handful has been detonated since 1992. Of the nine countries possessing nuclear weapons, all but India, North Korea and Pakistan signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in 1996, prohibiting countries from carrying out nuclear weapon test explosions or any other nuclear explosion. Most experts agree that the treaty will prevent countries from developing advanced nuclear weapons or improving existing ones, and thus impede a nuclear arms race, curb nuclear weapons proliferation and strengthen the Nuclear Nonproliferation Treaty (NPT). Many states parties to the NPT see the CTBT as a step towards nuclear disarmament, which they believe is required under the NPT in exchange for their agreement to forego nuclear weapons.
The CTBT contains extensive provisions for verification. An International Monitoring System (IMS), which is composed of 321 stations in 89 different countries, is a globally linked network that uses three acoustic waveform techniques to monitor under ground with 170 seismic stations, the atmosphere with 60 infrasound stations, and under water with 11 hydroacoustic stations. Two radionuclide techniques detect airborne radioactive particles and gases with 80 radionuclide stations and 16 radionuclide laboratories. Data from these stations are sent to an International Data Center in Vienna, where it is analyzed and screened. The Center produces an integrated analysis based on the fusion of data from the monitoring technologies on some 100 earthquakes and many mining and quarry events each day and regularly sends an “event bulletin” to states signatories. In the case of a suspected nuclear test, the treaty provides for a consultation and clarification procedure and, if that is inconclusive, an on-site inspection.
The verification provisions of the CTBT are more far reaching than those of other treaties, such as the Partial Test Ban Treaty, the Biological Weapons Convention, the Strategic Offensive Reductions Treaty, the five nuclear weapon-free zones, and the NPT. The on-site inspection regime is more complex than other international arms control treaties, involving the deployment of tons of sophisticated equipment for a period of up to 130 days.
As of January 2012, 182 countries have signed and 156 have ratified the treaty. The treaty will enter into force once 44 specified countries (that participated in the negotiations and, at the same time, possessed nuclear power reactors) have ratified it. Eight countries remain on this list: China, Egypt, India, 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 suit. The U.S. Senate did not provide its consent to ratify the treaty in 1999, and the Obama administration recently began the process of raising awareness of the treaty in the Senate. Opponents of the CTBT in the United States believe that the CTBT would diminish the confidence in the reliability of the nuclear weapons stockpile, thereby reducing the credibility of the U.S. nuclear deterrent. They also do not believe that the treaty is verifiable.
More than 85 percent of the 337 seismic, radionuclide, hydroacoustic, and infrasound monitoring stations and laboratories of the CTBT IMS have been installed and some of these networks are unique. The seismological component provides detection capabilities significantly beyond what was generally expected during the negotiations. The IMS was designed to provide good and roughly equal coverage of the globe to all states. It is an important tool for all countries, including those that have extensive national monitoring assets, because it provides data from areas of the world that would be difficult for them to obtain.
Contrary to the NPT and the International Atomic Energy Agency, verification of the CTBT rests with the states members, not the Technical Secretariat of the CTBT Organization implementing it. In the analysis of detection and deterrence from a state perspective, states can build on what the IMS provides and go even further. While the Secretariat of the CTBT Organization is limited to the use of IMS data only, and must treat the global data in a similar fashion, a state can focus on a specific area and can achieve a higher capability. The treaty allows countries to use information from the thousands of stations that are outside of the IMS, as well as satellite data and other national technical means that are not included in the IMS to help them determine compliance with the treaty. They can use such information as a basis for their request for an on-site inspection.
In a recent book by Ola Dahlman, Jenifer Mackby and others, Detect and Deter: Can Countries Verify the Nuclear Test Ban? (Springer 2011), the authors, who worked on the negotiations and implementation of the Treaty, note that with the dramatic developments in science and technology, states can use such focused methods of “precision monitoring” to achieve a monitoring capability far beyond that provided by the treaty’s IMS. States could improve the detection and deterrence capabilities by focusing their monitoring on specific areas of concern. The precise location of an event is of critical importance for a successful on-site inspection, and precision monitoring would reduce the uncertainty using carefully located reference events in the area.
This book notes that events down to magnitude 3.5 can be detected with a 90 percent probability using IMS data in most of the Northern Hemisphere, corresponding to a yield well below a kiloton in hard rock. An evader who would like to test clandestinely will certainlynot test if the probability of detection is 90 percent. He might not even accept a 10 percent risk of detection, at which level the IMS has a corresponding detection capability of magnitude 3.0. If all available stations were used, including those outside of the IMS, the capabilities would improve further, providing deterrence and confident detection down to a very low magnitude or explosive yield.
The greatest area of concern regarding nuclear testing is under ground. This is because there is a high monitoring capability in the underwater and atmospheric environments, down to very low explosion yields using the IMS hydroacoustic and infrasound networks. For example, hydroacoustic signals from a 100-pound underwater explosion can be observed across an ocean at distances of 10,000 kilometers.
States having the same political concerns and priorities regarding CTBT verification could cooperate in establishing joint monitoring centers rather than each using valuable resources to build their own national facilities. This could be carried out on a regional basis, for example, within the frame of the nuclear weapon-free zone treaties and the European Union Common Foreign and Security Policy (EU CFSP). Such cooperation would provide countries an efficient and cost-effective monitoring capability. It would also significantly increase the accumulation of knowledge among scientists around the world. This scientific expertise will be an important factor for countries represented in the Executive Council of the CTBT Organization that will consider requests for on-site inspections.
Once the treaty enters into force, the conduct of an on-site inspection must be initiated by states parties—not by the Technical Secretariat--who will bring a concern about noncompliance to the Executive Council, which will decide whether to carry out an on-site inspection. It is important that states send experts possessing technical knowledge so that the discussion and voting in the Executive Council will be based on factual information rather than becoming a political exercise. Thus, it behooves all states to acquire such expertise.
The possibility of using satellite observations to monitor the CTBT has increased significantly since the Treaty was negotiated. A number of open satellite systems are operational that provide good coverage with repeated observations of a scene within one or two days. Optical satellites provide resolution down to 1 meter and radar satellites (which provide coverage even through clouds) down to 10 meters. The most dramatic development is that data from these systems are readily available at low cost. A relatively new technology, InSAR, may make it possible to detect very small changes in ground elevation that might result from underground explosions.
In addition, while the CTBTO International Data Center is constrained in the way it analyzes data, countries are not. Countries can apply new analysis techniques to improve on the analysis and interpretation of such data to focus on 2the areas selected. They can fully utilize data mining, and draw on IMS auxiliary and non-IMS data for event detection and exploit these developments to provide the best possible capability for events in selected areas. Thus, a state can choose an area of concern, choose the stations it wants to use for analysis of an event, and apply the data analysis methods it desires in order to create its own “network.”
Calls to stop testing began soon after the development of the bomb in the 1940s. Indian Prime Minister Jawaharlal Nehru formally proposed an agreement to stop testing at the United Nations in 1954, and a number of attempts to negotiate a CTBT were pursued between then and the time the treaty was agreed on at the United Nations in 1996, only to fail over political or verification questions. It remains to be seen whether the CTBT will continue as a norm or enter into force, or whether future generations will continue to pursue the goal.