Many of the specific questions raised about our article’s limitations by the commentators are, indeed, true, but they reflect the stated approach of the paper. North Korea is a country where the uncertainties are great, and this is no truer than in trying to anticipate a future North Korean government collapse and potential transition to Korean unification. Moreover, information on North Korea is scarce and difficult to interpret in large part because of North Korean information denial and falsification efforts. As a result, it is important to note our statement of the purposes of our article: “First, we seek to bring into the public debate a discussion of the scale of the problems that the collapse of North Korea’s government could create, and the potential for dire consequences, both humanitarian and strategic, if stability efforts were delayed or failed altogether. We describe the military missions that might be necessary to stabilize North Korea and estimate the force requirements for those missions. … Second and more broadly, this analysis sheds light on international intervention in collapsing states.” (86) With their comments, the reviewers have certainly contributed to our first objective, and their comments add to what we have contributed on the second. Moreover, we developed estimates of the military force requirements because we felt they would help motivate a public debate.
This edited volume makes a unique contribution to the field of American foreign policy by bringing together scholars and policy makers to assess two key turning points in American politics: the fall of the Berlin Wall in November 1989 and the terrorist attacks of September 11, 2001. As the editors, Melvyn P. Leffler and Jeffrey W. Legro, write, “The aim of this book is to extrapolate from the aftermath of the most dramatic events in recent international history for the purposes of improving strategic thinking and strategic planning.” (3) Foreign-policy crises typically prompt reassessments of U.S. interests and priorities, and the editors aim to identify how those efforts can be better informed by those who develop policy and those who evaluate it (and several contributors to the volume have been active in both areas).
With The Threat on the Horizon, Loch Johnson adds to his distinguished record of publications on the topic of United States intelligence. The book is part monograph, examining the Aspin-Brown Commission tasked with reforming intelligence in the 1990s; part autobiography, drawing on Johnson’s role as the Chairman’s assistant on the Commission; and part policy analysis, using the first two sections to draw out more general observations on the intelligence process.
Samuel Moyn’s study of human rights movements is a path-breaking book. It moves the study of human rights out of the realm of virtue and into the realm of politics. By desacralizing the subject, he has historicized it, and thereby has enabled us to measure the claims of human rights against other political claims and projects. Trained both as a lawyer and as an intellectual historian, Moyn tilts the chronology of human rights history towards a bifurcation, between a period of failed activism prior to 1970 and of successful mobilization in the form of a set of popular trans-national movements after that date. Why the divide? Because prior to 1970, other utopias, especially the Marxist one in Europe and elsewhere, as well as its anti-colonial variants in Asia, Africa, and Latin America, still commanded the loyalty and commitment of millions. After that date anti-colonialism had more or less completed its historical mission, and Marxism, as a theory of action and as a political movement, slowly and then spectacularly collapsed. Into the vacuum rushed human rights as a political weapon of choice.
Bruce Bennett and Jennifer Lind provide what can only be described as a most timely analysis of the challenges facing external actors in the event of a collapse in North Korea following “the most difficult challenge that such regimes face: succession” (84).They correctly identify not only the internal weaknesses of the Democratic People’s Republic of Korea (DPRK) and the daunting prospect of a truncated transition period, but also the difficulties and dangers faced by the international community in addressing a potential collapse. Underlying trends leading to collapse include the destabilizing effects of a chronic lack of food combined with uncertainty about who is in power (91). The authors see Kim Jong-il’s sudden death or incapacitation as the potential trigger for a power struggle and subsequent government collapse, due to the limited time spent grooming his successor, Kim Jong-un, and the candidate’s extreme youth (84). And a “government collapse in North Korea could unleash a series of catastrophes on the peninsula with potentially far-reaching regional and global effects” (84). These effects would include a humanitarian crisis leading to a massive outflow of refugees, North Korean weapons of mass destruction (WMD) finding their way onto the international black market, and, potentially, in the absence of sufficient international coordination, conflict between the countries likely to intervene, the People’s Republic of China, the Republic of Korea, and the United States (85).
Nicolas Guilhot and Ido Oren both contribute useful insights, in the paper Guilhot published in Behavioral Sciences, and in Oren’s review of it here. I would like to offer a more personal perspective based on my own experience. As a young History student at Columbia College from 1969 to 1973 I did, nevertheless, hover on the edges of the Political Science Department and its Institute of War and Peace Studies, the hotbed of IR at Columbia. From 1973 to 1981 I was a graduate student in IR at the Institute—and a direct observer of all of this. William T. R. Fox was my mentor, seconded by the nuclear weapons theorist Warner R. Schilling. Fox’s impact on the field has been dimmed by time but merits greater attention—it was he, after all, who coined the term “superpower,” and whose participation in a study group with Bernard Brodie led to the first systematic attempt to consider the international implications of the atomic bomb in The Absolute Weapon.
Nicolas Guilhot has established himself as arguably the leading disciplinary historian of post-World War II international relations (IR). In an earlier, “must-read” essay Guilhot painstakingly documented how, in the 1950s, the Rockefeller Foundation bankrolled a network of realist scholars and practitioners who set out to build a theory of IR. Although they could not agree on the meaning of “theory,” members of the group, including Hans Morgenthau of the University of Chicago and William Fox of Columbia University, were nearly all opposed to the creed that Morgenthau famously attributed to “scientific man”: the “conception of the social and physical world as being intelligible through the same rational processes” and the attendant view that “the social world is susceptible to rational control conceived after the model of the natural sciences.” Guilhot cogently interpreted the group’s effort to “theorize” IR as a defensive reaction to the surge of the behavioral movement in the social sciences, a movement that appeared to embrace the creed of “scientific man” and that was generously funded by the Ford Foundation. For Morgenthau and his associates, creating “IR theory” was a way of delineating “an independent disciplinary territory” for the field, rendering it “immune to the cues of behavioralism.” 
If successful grand strategy requires balancing a state’s commitments and its resources, a great power in decline might be expected to retrench. According to Paul MacDonald and Joseph Parent, however, the conventional wisdom is that retrenchment rarely occurs and, when it does, rarely succeeds. “Retrenchment pessimists,” they note, contend either (1) that strategic retrenchment is dangerous because it signals weakness and invites attack, or (2) that retrenchment is desirable, but cannot be achieved because of domestic cultural and/or political constraints (9-10).
Thomas Christensen has written an important book in which he examines several key episodes during the Cold War in Asia, including the Korean War, the Taiwan Strait crises of 1954–55 and 1958, and the Vietnam War. In Worse than a Monolith, Christensen uses these Cold War flashpoints to test and refine existing theories of alliance politics and coercive diplomacy, arguing that a state’s use of coercive forms of diplomacy, including containment and deterrence, is hampered when one’s adversaries are divided. Christensen finds ample fodder for this argument by focusing Worse than a Monolith on looking at America’s efforts to contain the “revisionist” communist alliance during the Cold War in Asia. Disagreements between Moscow and Beijing often caused the two to try to outdo each other in supporting revolutions such as the one in Vietnam, and from the perspective of America’s policy makers, this made the communist alliance “worse than a monolith.” Christensen’s thesis is intriguing. I am interested to know whether during the Cold War, leaders on one side or the other expressed the view internally that they were bedeviled by their adversary’s inability to control its “troops.”
While knowledgeable observers rightly discounted the geopolitical significance of China’s launch of the refurbished Russian aircraft carrier Varyag last August, the event did underscore the salience of the topic of this H-Diplo roundtable. No student of international relations can be indifferent to the questions that Michael Horowitz addresses in Diffusion of Military Power. Will China ultimately develop true carrier warfare capacity? Why has U.S. supremacy in this area gone unchallenged for over half a century? How likely is it that China will emulate other aspects of U.S. military power? How many new nuclear powers are we likely to see? Will Iranian drones soon patrol American skies? Horowitz develops and tests a bold structural- and material interest-based theory to explain the propensity of military innovations to diffuse through the international system.