CTBT Verification Issues


2012-09-26 By Richard Weitz

The Comprehensive Test Ban Treaty (CTBT) will have independent instruments for verifying and enforcing the treaty once it enters into force.

These will supplement the verification provided by countries’ national technical means such as reconnaissance satellites as well as other intelligence collection systems. Much of the prior U.S. ratification debate concerned the issue of whether these measures are adequate.

Article II of the treaty creates a Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in Vienna to manage CTBT implementation. It consists of three main organs. One of them, the Technical Secretariat, operates an International Monitoring System (IMS), which is a global network of monitoring stations linked to an International Data Center in Vienna. The secretariat also conducts on-site inspections and administers the various consultation, clarification, and confidence-building measures detailed in Article IV and the CTBT Protocol designed to verify the treaty’s implementation.

Article IV of the CTBT specifies that the CTBTO IMS will consist of 321 stations distributed throughout the globe. They employ multiple technologies to detect signals typically emitted by nuclear explosions: 170 seismic stations (of which 50 primary facilities operate continuously while 120 auxiliary stations provide data when requested by the IDC to detect underground seismic waves; 11 hydroacoustic stations to detect underwater sound waves; 60 infrasound stations to monitor low frequency atmospheric sound waves; and 80 radionuclide stations—supported by 16 on-call radionuclide laboratories—that together identify and analyze radioactive particles and gases in air samples indicative of a nuclear explosion. Annex I of the CTBT Protocol provides a detailed list of each facility’s location and type.

The Preparatory Commission has already begun constructing a network of monitoring stations worldwide that will transmit information to a CTBTO-run international data center in Vienna that would share this intelligence with the treaty signatories.

Treaty parties would also have access to information provided by scientific and other civilian monitoring networks as well as their national technical means of verification.

The Vienna data center employs advanced data management and systems integration techniques to collect, analyze, and archive the information from the IMS stations as well as distribute the data to subscribing national authorities.

The Verification Data Acquisition System VDAS is a commercial-off-the-shelf (COTS) distributed, open-architecture system addressing the special needs of the nuclear treaty verification community. http://www.kinemetrics.com/p-42-vdas.aspx

When the remote IMS sensors yield suspicious or uncertain results, the CTBT provides for short-notice challenge inspections at the site of the possible explosion and other means to resolve cases of suspected treaty violations. The CTBTO is developing its own on-site inspection capacity for this purpose, with detailed procedural manuals, special equipment, and a roster of potential inspection team members available from the member states.

To discourage use of the inspection mechanism for political propaganda or other improper purposes, requests for on-site inspections must be approved by at least 30 affirmative votes of the countries serving on the CTBTO’s 51-member Executive Council.

To avoid compromising the legitimate national security interests of the country under inspection, the examination must be conducted in the least intrusive manner possible.

The hosting government can also restrict inspectors’ access to sensitive installations and confidential information unrelated to the purpose of the inspection.

If a violation is determined to have occurred, the parties can use CTBT-sanctioned dispute resolution mechanisms, impose limited sanctions, or present the matter to the UN Security Council. The Council can then mandate a range of enforcement actions, including the use of military force.

The CTBTO has organized various exercises and other demonstrations of the verification regime’s effectiveness. From September 1-25, 2008, the CTBTO conducted a mock inspection exercise at the former Soviet nuclear test site of Semiapalatinsk in northern Kazakhstan. The scenario posited that the CTBTO International Monitoring System detected seismic signals that might result from secret nuclear tests in the fictional Central Asian republic of Arcania. Although the Arcanian authorities attributed the shock to an earthquake, the government of a neighboring country formally requested that the CTBTO conduct an on-site inspection to determine whether a nuclear explosion had occurred in violation of the CTBT. The 40 members of the team then rehearsed the procedures and technologies they would employ in a real on-site challenge inspection conducted under CTBTO auspices.

Opponents of the CTBT have long cited perceived difficulties in verifying compliance with its terms—which include a proscription against hard-to-detect low yield underground nuclear explosions, which might resemble earthquakes, conventional explosions (e.g., for mining), or other non-nuclear events—as a decisive argument against the treaty’s ratification. 

Opponents of the treaty consider the capabilities of the IMS insufficient to detect all militarily significant clandestine nuclear tests, especially those employing various evasive techniques such as detonating the weapons in large underground cavities (de-coupling) or outside national territories.

They also fear that CTBTO members would refuse, for political or other illegitimate reasons, to authorize on-site inspections of suspect nuclear detonations. They believe that rogue states would violate the CTBT as readily as they disregard their NPT obligations.

Treaty opponents further point out that, if a nuclear test presents a threat to international peace and security, the UNSC can address the problem directly (as occurred after the October 2006 North Korean test) without a referral from the CTBTO, whose verification and confirmation deliberations might delay UNSC action.

Some CTBT critics have favored formally withdrawing the American signature and resuming testing to ensure the reliability of the aging U.S. nuclear stockpile as well as to design new warheads and nuclear weapons that are more safe and reliable. Customary international law generally is interpreted as not permitting a country that has signed but not yet ratified a treaty to pursue actions that undermine the accord’s fundamental purposes.

Conversely, treaty proponents maintain that the technologies for verifying nuclear tests have developed to the point that any CTBT-related cheating would almost certainly be caught. Even if a very small nuclear test escaped detection, they argue that it would have little effect on the overall strategic balance and would in any case present less of a danger to global security than the current environment in which countries can test multiple-kiloton nuclear weapons without violating any existing arms control accord.

Treaty supporters agreed with the Bush administration about the value the IMS detection architecture, but worry that a failure of the United States and other countries to ratify the CTBT could undermine funding and support for its construction and maintenance.

Since the IMS is under international control, moreover, CTBT supporters argue that its findings regarding possible nuclear explosions would probably be more credible than those offered by a single national government, whose interpretation might reflect political or other biases and whose own sensor network would be less extensive than that of the IMS (which requires more than one billion dollars and over a decade to construct).

In March 2012, the National Academy of Sciences issued a report that stated that technical advances since 1999 have enhanced the U.S. ability to verify the treaty. It also concludes that the Stockpile Stewardship Program “has been more successful than was anticipated in 1999,” when the Senate last considered the CTBT.

The report concludes that “[c]onstraints placed on nuclear-explosion testing by the monitoring capabilities of the IMS and…U.S. NTM [national technical means of intelligence] will reduce the likelihood of successful clandestine nuclear-explosion testing, and inhibit the development of new types of strategic nuclear weapons.”

The study concluded that an on-site inspection as permitted under the CTBT once it enters into force “would have a high likelihood of detecting evidence of a nuclear explosion with a yield greater than 0.1 kilotons, provided that the event could be located with sufficient precision…and conducted without hindrance.”

The panel said on-site inspection “constitutes a deterrent to treaty violation whether or not an inspection actually takes place.”

Nonetheless, the report stated that “the development of weapons with lower capabilities…is possible with or without the CTBT for countries of different levels of nuclear sophistication.”

However, it adds that “such development would not require the United States to return to nuclear testing in order to respond because it already has—or could produce—weapons of equal or greater capability based on its own nuclear-explosion test history.”