In talks with the United States late in February, North Korea agreed to suspend its uranium enrichment in a specific facility at Yongbyon and to initiate a moratorium on nuclear and long-range missile tests. When the United States and North Korea made the bilateral "leap-day deal," the suspension of enrichment was rightly hailed as one of the great successes of the arrangement. Since 2006, North Korea has tested missiles, staged two nuclear tests, and unveiled a uranium enrichment program that could give it a second route to manufacture nuclear weapons, in addition to its existing plutonium-based program. At low enrichment levels, uranium can be used in power reactors, but at higher levels, it can be used in nuclear bombs.
Beginning in negotiations with North Korea early in the 1990s, the international community has increasingly relied on the suspension of nuclear-material production as an ad-hoc, but important, confidence-building measure that can open space for negotiations with suspected proliferators. Unfortunately, suspension of nuclear activities remains a flimsy, ill-defined concept. It is a voluntary measure -- a state can't be legally obliged to suspend its activities -- and there are no agreed international regulations that define what it entails or how it should be monitored and enforced. Also, there are significant risks of diversion of material during suspension. Given the growing popularity of suspension as a nonproliferation mechanism, the international community must now ensure that the International Atomic Energy Agency (IAEA) has the tools to guarantee that suspension is not a fig leaf for covert or illicit activities.
The international community essentially invented the concept of suspension in 1993, when it convinced North Korea to put a hold on its nuclear activity. At the time, the IAEA tried to verify that no nuclear material production would occur during the suspension, but without great success. This uncertainty put strain on negotiations, which eventually collapsed when North Korea announced it would withdraw from the Nuclear Non-Proliferation Treaty in 2003. North Korea blamed the United States for failure to fulfill its end of the Agreed Framework, a 1994 agreement between the states to limit North Korea's nuclear ambitions, to begin normalization of relations, and to help supply some of North Korea's energy needs.
Part of the problem in using suspension of nuclear material production as a negotiating step is obvious: Suspension has never been clearly defined. For uranium enrichment facilities, does it mean that centrifuges can continue to spin without material, or must they completely stop? How is the amount of nuclear material in the pipelines at the moment of stoppage verified, and how can it be guaranteed that the same amount is removed if decommissioning occurs? How can inspectors verify that a country does not perform undeclared activities during suspension, such as bringing undeclared feed into the plant for enrichment for undeclared production of highly enriched uranium? How can a country be prevented from removing essential equipment or diverting nuclear material stored in a facility under suspension to clandestine, undeclared facilities?
The IAEA has been safeguarding gas centrifuge enrichment facilities for more than 25 years. Unfortunately, the measurement of the amount and the enrichment level of nuclear material in uranium enrichment facilities remains one of the principal safeguards challenges. Performance values for non-destructive assay techniques contain systematic uncertainties and can vary from 2 percent to 10 percent, depending on measurement conditions, on the evaluation and measurement procedures used, and on the calibration standards available. The IAEA needs to develop new methods and equipment that will reduce measurement errors.
In the case of suspension, the problem of determining how much material has been enriched to what particular levels is even more acute; countries agreeing to suspension probably have or have had weapons aspirations. For that reason, inspections should be even more intrusive than normal during a suspension of enrichment. The containment and surveillance equipment that the IAEA uses when monitoring an operational nuclear facility (including cameras, seals, and detectors) is not necessarily sufficient to ensure that diversion of material or equipment does not occur during a suspension. The only way to ensure compliance with suspension is to insist on the dismantlement and sealing of all equipment in those parts of the facility that are most sensitive. In particular, the feed supply system, the product recovery system, and the electric supply should be verifiably dismantled as standard procedure during the suspension of an enrichment facility. It is crucial for inspectors to be constantly present during the suspension period.
The international community needs to be aware of the diversion risks during suspension of enrichment activities and should mitigate these risks by including the necessary verification measures during negotiations and signing of any agreement on suspension. Toward that end, the IAEA should prepare a policy paper that addresses the issue of safeguards measures applicable before and during suspension. The paper should be part of the subsidiary agreements between the IAEA and the country that is suspending enrichment and should be as binding as the original Safeguards Agreement. Dealing with, and avoiding proliferation risks from, suspended nuclear enrichment facilities will be an important part of international nonproliferation efforts in upcoming months -- not only in North Korea, but in Iran and possibly elsewhere.