We develop a mathematical model to find the optimal inspection strategy for detecting a nuclear weapon (or nuclear material to make a weapon) from being smuggled into the United States in a shipping container, subject to constraints of port congestion and an overall budget. We consider an 11-layer security system consisting of shipper certification, container seals, and a targeting software system, followed by passive (neutron and gamma), active (gamma radiography), and manual testing at overseas and domestic ports. Currently implemented policies achieve a low detection probability, and improved security requires passive and active testing of trusted containers and manually opening containers that cannot be penetrated by radiography. The annual cost of achieving a high detection probability of a plutonium weapon using existing equipment in traditional ways is roughly several billion dollars if testing is done domestically, and is approximately five times higher if testing is performed overseas. Our results suggest that employing high-energy x-ray radiography and elongating the passive neutron tests at overseas ports may provide significant cost savings, and several developing technologies, radiation sensors inside containers and tamper-resistant electronic seals, should be pursued aggressively. Further effort is critically needed to develop a practical neutron interrogation scheme that reliably detects moderately shielded, highly enriched uranium.

To reduce the risk of nuclear terrorism, we must prevent terrorists from obtaining nuclear weapons or materials. This will require, among other things, a sustained effort to keep dangerous nations from going nuclear--in particular North Korea. This article reviews the efforts the United States has undertaken through the years to keep North Korea from building a nuclear arsenal, arguing that the history of proliferation on the Korean Peninsula is marked by five nuclear crises. A sixth could be on the horizon, further compromising American efforts to lessen the likelihood of a nuclear attack on U.S. soil.

One of the serious risks associated with the strategic nuclear arsenals of Russia and the United States is that an accidental launch might result from a false alarm or from misinterpreting information provided by an early-warning system. This risk will not be reduced by bringing down the number of strategic missiles on high alert to the level of about 500 warheads on each side because this measure will not significantly affect first-strike vulnerability of the Russian strategic forces. Other measures that have been suggested so far, namely an upgrade of the Russian early-warning system, establishing additional channels of real-time exchange of early-warning data, or transparent and verifiable de-alerting of strategic forces, are more likely to increase the probability of an accident than to reduce it. To address the problem of an accidental launch in the short term, the United States and Russia, while continuing to work toward deep reductions of their strategic nuclear forces, should develop and implement measures that would keep their entire forces at low levels of readiness without revealing their actual alert status.

The nexus of terrorism and nuclear weapons is today's greatest security concern. The importance of keeping fissile materials out of the hands of terrorists is now generally accepted. The difficulty of doing so is not. Lack of appreciation, especially for the technical difficulties, is hampering our ability to build a comprehensive safeguards system and prevent nuclear terrorism.

The debate over how to deal with Iran's nuclear program is clouded by historical amnesia. Nuclear proliferation has been stopped before, and it can and should be stopped in this case as well. Unfortunately, with Tehran -- as with some of its predecessors -- the price for Washington will be relinquishing the threat of regime change by force.

Authors should always be so fortunate as to have such thoughtful and stimulating readings of one's work. What follows: Eden turns some comments by Renee Anspach, Hugh Gusterson, and Thomas Hughes into invitations to do further research. She then discusses organizational frames in the context of other conceptions of frames. Last, she tackles the difficult issue of taking a stand on the science in Whole World on Fire(Eden, 2004) while claiming to be a thoroughgoing social constructivist.

Lynn Eden received the 2005 Robert K. Merton Professional Award from the Science, Knowledge & Technology Section of the American Sociological Association (ASA), for her book Whole World on Fire: Organizations, Knowledge, & Nuclear Weapons Devastation (Cornell University Press, 2004). The book was featured in an Author Meets Critics session at the 2005 ASA meetings in Philadelphia, with Renee Anspach, Hugh

Gusterson, and Thomas P. Hughes as the critics. The journal invited the participants to submit their comments for a review symposium published in Social Studies of Science, and was delighted to receive the review essays from Professors Anspach, Gusterson, and Hughes, and the reply from Professor Eden.

Nuclear terrorism is the common enemy of all mankind, and its danger is a reality. In the face of the emergence of global, non-state terrorism, China must be prepared to confront a new kind of enemy -- the nuclear terrorist. There are several potential forms of nuclear terrorism. A terrorist attack using a functional nuclear device would be devastating. A "dirty bomb" is another form, although much less deadly and far easier to build than a crude nuclear device. China believes that to combat nuclear terrorism, the most important thing is to enhance nuclear materials control and their security. China has taken substantial measures to further strengthen its control over nuclear materials as well as to protect its nuclear facilities. In the face of this new challenge of combating nuclear terrorism, there is still much work for China to do, including improving management and control of radioactive sources and clarifying the design basis threat. In all, every nation must not only perform its due obligations to prevent nuclear terrorism, but also participate actively in building international nonproliferation and nuclear security regimes. All countries should take unanimous action, And China will continue to contribute to this end.

This article is based on a paper the author researched and wrote as a 2004-2005 visiting scholar with the Project on Peace and Cooperation in the Asia-Pacific Region at CISAC.

This is the fourth and final volume in a pioneering series on the Chinese military. It begins with an examination of Chinese military culture and history, with special attention to the transition from Mao Zedong's revolutionary doctrine and the conflict with Moscow to Beijing's preoccupation with Taiwanese separatism and preparations for war to thwart it. Because such a war might involve the United States, the Chinese have concentrated on measures to deter American intervention. Part II focuses on the military and decisionmaking, first in the National Command Authority and then in the People's Liberation Army's command-and-control prioritizing system. Part III provides a detailed study of the Second Artillery, China's strategic rocket forces. Based in part on interviews, the book provides an unprecedented look at its history, operational structure, modernization, and strategy. This is followed by a historical account of the air force's long effort to modernize and its role in joint operations and air defense. The book concludes with the transformation of military strategy and shows how it is being tested in military exercises with Taiwan and the United States as "imagined enemies."

A Chinese translation by Litai Xue was published by Mirror Books, Hong Kong, in 2007.