A post-9/11 study by the National Research Council (NRC), Making the Nation Safer: The Role of Science and Technology in Countering Terrorism, concludes that such detection is technically feasible: “The technology for developing [post-explosion nuclear attribution] exists but needs to be assembled, an effort that is expected to take several years.”

Nuclear Forensics: Role, State of the Art, Program Needs, a 2008 study by the Joint Working Group of the American Physical Society (APS) and the American Association for the Advancement of Science (AAAS) that is the best recent public report on the subject, concurs with the NRC’s judgment: “The underlying scientific disciplines … are understood adequately for the purpose of forensics.” Nevertheless, the report concludes that the current state of the art will not yield maximally effective deterrence. We lack a central global database of unique material signatures that countries can promptly access in the event of a nuclear detonation. Even if such a database existed, states would not be fully prepared to take advantage of it in a day-after scenario. The APS and AAAS report that “neither equipment nor people are at the level needed to provide as prompt and accurate information for decision makers as is possible.”

The report suggests that two separate technological initiatives are critical to improving U.S. forensic capability. The first is the development of equipment that can provide immediate, rough assessments in the field–portable instruments ­capable of what the APS and AAAS call “all-weather, all-­scenario rapid response.” The second is improvement of equipment for performing more detailed analysis of forensic samples. According to the report, the equipment in the U.S. Department of Energy’s labs must be upgraded to “world standards.”

Assuming that there is an attack and we have identified the source, we come to the much more difficult question. What response is appropriate?

A Global Alliance Against Nuclear Terrorism
Establishing an accepted principle of nuclear accountability will be a major international undertaking. It should begin with the United States and Russia, each of which has a special obligation to address this challenge, since they created it–and since they still own 95 percent of all nuclear weapons. They should take the lead in establishing a new global alliance against nuclear terrorism. The mission of the alliance should be to minimize the risk of such terrorism anywhere by taking every action physically, technically, and diplomatically possible to prevent nuclear weapons or materials from falling into the hands of terrorists.

Membership in the alliance would require an unambiguous commitment to the principle of assured nuclear security. States would have to guarantee that all nuclear weapons and materials in their territories were beyond the reach of terrorists or thieves. And states’ means of securing these materials would have to be sufficiently transparent that leaders of all member states could reassure their own citizens that terrorists would never get a nuclear bomb from another alliance member.

U.N. Security Council Resolution 1540 already obligates all member states to develop and maintain “appropriate, effective” measures to secure weapons and materials, but this obligation has unfortunately not been reinforced by specific, mandatory standards. However, the Nunn-Lugar Expansion Act, adopted by Congress in 2003, authorized the Nunn-Lugar program to operate outside the former Soviet Union to address proliferation threats. Moreover, the Bush administration has reportedly provided $100 million in technology and related assistance to help Pakistan secure its vulnerable nuclear arsenal.

The Global Initiative to Combat Nuclear Terrorism announced by Presidents Bush and Putin at the St. Petersburg G8 summit in July 2006 was another step in the right direction. But the alliance against nuclear terrorism that I am proposing would go beyond declarations; it would require specific actions in exchange for specific benefits. The actions would include defining the security levels of weapons and ­weapons-usable materials, as well as assuring others that these levels of security had been achieved. Leaders of complying states would participate in an annual summit, and full alliance members would also be entitled to intelligence sharing, assistance with security technology, participation in interdiction exercises, and postdetonation medical and cleanup aid.