The official U.S. government policy is to maintain "calculated ambiguity" about whether the United States would retaliate with nuclear weapons in response to an adversary's use of chemical weapons (CW) or biological weapons (BW) against U.S. allies, U.S. armed forces overseas, or the U.S. homeland. Since the 1991 Gulf War, numerous civilian and military leaders have stated that the United States might use nuclear weapons in response to CW and BW threats or attacks, and some have even stated that the United States will use nuclear weapons in such circumstances. The central argument in my spring 2000 International Security article was that this policy has created a dangerous "commitment trap" problem.

The benefit of making such nuclear threats, whether stated ambiguously or clearly, is that they can increase an adversary's estimate of the probability that the U.S. president would order nuclear retaliation, which should therefore decrease the likelihood of chemical or biological weapons attacks. But there is a serious cost attached to this obvious benefit: If deterrence fails despite nuclear threats, the statements will also increase the likelihood that the United States will actually use nuclear weapons, because the president's personal and the U.S. government's institutional reputations for following through on threats would be perceived to be at stake.

I argued that current U.S. nuclear doctrine has therefore created a subtle dilemma that has not been recognized, much less debated, in both policy and academic circles: Is the improvement in the U.S. ability to deter CW and BW threats worth the increased likelihood of a U.S. nuclear response if deterrence fails?

A biological terrorist attack probably would first be detected by doctors or other health-care workers. The speed of a response would then depend on their rapid recognition and communication that certain illnesses appeared out of the ordinary. For this reason, preparing for biological terrorism has more in common with confronting the threat of emerging infectious diseases than with preparing for chemical or nuclear attacks. Defense against bioterrorism, like protection against emerging diseases, must therefore rely on improved national and international public-health surveillance. Too often, thinking about bioterrorism has mimicked thinking about chemical terrorism, a confusion that leads to an emphasis on the wrong approaches in preparing to meet the threat.

A joint Stanford University-Lawrence Livermore National Laboratory team of scientists, nuclear engineers and arms control experts has concluded in a new study that North Korea's compliance with the 1994 Agreed Framework can be verified to a satisfactory degree of accuracy. Special effort, however, will be needed from the International Atomic Energy Agency (IAEA), as well as support from the US, the Republic of Korea (ROK), Japan and perhaps other countries. Most importantly, cooperation and openness from North Korea are essential.

The 1994 Agreed Framework (AF) between the United States and the Democratic People's Republic of Korea (DPRK) has become the centerpiece of recent US efforts to reduce the threat of conflict on the Korean peninsula. Under the AF, the US and its allies (mainly South Korea) will provide the DPRK with two large nuclear-power reactors and other benefits such as annual shipments of fuel oil for the generation of electricity until the nuclear-power reactors being built for that purpose are able to do so. In exchange the DPRK will declare how much nuclear weapon-usable material it has produced; identify, freeze, and eventually dismantle specified facilities for producing this material; and remain a party to the nuclear Non-Proliferation Treaty (NPT) and allow the implementation of its safeguards agreement.

The AF is now being carried out according to a complex and currently delayed schedule. Fuel oil shipments have been provided to the DPRK, the site for the two nuclear-power reactors has largely been prepared, and construction has begun on some components. The DPRK, for its part, has declared some nuclear weapon-usable material and has identified and frozen some facilities for producing this material.

As emphasized in President Bush's statement at the White House on March 7, 2001, verification is an essential part of any agreement with North Korea. How well can it be verified that the DPRK has no access to nuclear weapon-usable material? What is the potential impact of delays, disagreements, and lack of cooperation on verification? The United States and the international community must answer these questions if the nuclear-power reactor project is to proceed as planned.

The report analyzes in detail both the task of safeguarding the nuclear-power reactors to be provided and also that of dealing with known or suspected nuclear-materials production facilities in the DPRK. Scenarios governing both DPRK cooperation and possible non-cooperation, up to and including abrogation of the agreement are considered.

The challenges of verification examined in this report must be met if a necessary minimum of trust is to be established between the parties and the rewards of the agreement are to be realized. The authors believe that the challenges can be met under the conditions outlined in this report, but that special effort on all sides will be needed to meet them.