Corden and Hafemeister reply: We are grateful to Roger Johnston and Richard Wilson for their comments. The applications of science and technology to nuclear nonproliferation and arms control are many; our article addressed only some of them. Tags and seals cannot stand alone in a verification system. We acknowledge that considerable care needs to be taken to deal with attempts to spoof them, whether from outside or by an “insider.” We endorse Johnston’s observation that further R&D is important. Johnston pointed out in 2001 that the integrity of tags and seals can be strengthened with technologies that include thin films, advanced polymers, liquid crystals, microparticles, electro-optic materials, nanotechnology, one-time key pads, and other approaches.1
Multiple signatures make tags and seals more robust. Clearly, some tags and seals that are more complex may be difficult for all International Atomic Energy Agency (IAEA) member states to accept. The US alone cannot dictate higher standards to the world, but it can work within the IAEA to upgrade safeguard technologies.
The concluding paragraph of our article briefly addresses the issues raised by Wilson on the lack of universality of the Nuclear Non-Proliferation Treaty (NPT), specifically with India and Pakistan and US foreign policies that have made reversing their nuclear programs more difficult. But it is not accurate to say that either state has not been subject to efforts to halt them over the years; for example, their economies were severely sanctioned by the US after their May 1998 nuclear tests.
The NPT is not a suicide pact. It speaks of the right to peaceful uses of nuclear energy and makes no mention of a specific right to enrichment or reprocessing. We think that the efforts of the international community to strengthen the constraints on Iran against its acquisition of nuclear weapons are appropriate, and we hope for their success. As physicists who have spent much of our careers in nonproliferation, arms control, and disarmament, we agree with Wilson’s point that the physics community should explain the policy implications of nuclear weapons issues. And working on resolving those issues is perhaps even more important.
Has the NPT process helped or hurt global proliferation? Certainly it initially enhanced technology transfer of plutonium manufacture, but it also gave the world a starting place to establish nonproliferation criteria and institutions to carry out inspections under the NPT and the IAEA. Further progress will make it easier to obtain nuclear technology, will lower the technical barrier to the bomb over time, and will increase the need for strong NPT and IAEA safeguards. And starting with the Carter administration in 1977, the US has worked mightily to constrain enrichment and reprocessing in non-nuclear-weapon states. A major concern is that the NPT is silent on the issue of ownership of the nuclear materials in states that withdraw from the NPT—North Korea, for example—and what to do about it. Problems are well known, but specific, viable solutions are needed.
