The vitriol has been flying across East Asia at an unprecedented rate in 2010-13. Following a 2012 edited book, East Asian National Identities: Common Roots and Chinese Exceptionalism, this second book in a three-volume series puts this pungent atmosphere in perspective. Shifting the focus from comparisons and the evolution of identities to dyads and the impact of national identities on international relations, this volume shows how in 2009-11 Chinese publications on Japan, South Korea, and the United States became much more negative. It offers a detailed look at the three bilateral relations involving China, Japan, and South Korea and an intense focus on how China's national identity impacts three national identity gaps still in flux.

The central concept is national identity gaps, indicating how substantial and sensitive differences in identity are for bilateral relationships. Some states achieve special meaning in the way they are treated as part of the identity of another state. That is the case in East Asia where states are "significant others" to each other. Gaps are analyzed on five dimensions of national identity and are estimated over time for each dimension, enabling calculation of their intensity as the sum of these estimates. Although gaps have generally widened in recent years, the most visible change has been the impact of more assertive Chinese national identity on the gaps with three countries. Since 2009 China has become the driving force in identity transformation.

Part I offers five perspectives, beginning with how Japan's national identity led it to search for a breakthrough that would reduce its sense of abnormality due to the shadow of U.S. national identity and its legacy of imperialism in Asia, and ending with China's revival of "tianxia" (the doctrine of "all-under heaven" seen as the basis of the tributary system) in order to articulate a more distinctive, superior national identity. Along with these chapters by Togo Kazuhiko and Zheng Yongnian, there are three chapters assessing how national identities are shaping bilateral ties by Ming Wan, Cheol Hee Park, and Scott Snyder and See-Won Byun. These chapters make a strong case for why changing relations within East Asia are highly dependent on identities. They show the changing impact on Sino-Japanese, Sino-South Korean, and Japanese-South Korean relations of the recent transformation of national identities.

Half of the book-the introductions to Parts I and II and my three chapters on international relations studies, the impact of Chinese national identity on East Asian national identity gaps, and its impact on demonization of the United States-presents a framework for applying national identity analysis to the study of foreign policy. I concentrate on recent Chinese writings after Part I's broader coverage of Japanese, South Korean, and Chinese views over a longer time frame. In recent years Japan has continued to make identity a focus and South Korea has done this too. Yet, Chinese publications reveal a much greater obsession with identity differentiation.

A review of recent identity gaps can draw attention to how this framework is applied. Given the focus in the book on widening gaps, the introduction to Part II has special meaning for its attempt to compare the size of the gap over time and across the different bilateral relations under examination. A scale of 0-5 is utilized for each of five dimensions with a total of 0-25 recorded as their sum and a measure of the intensity of the divide between two countries. The divides are large in this region.

Estimates on the ideological dimension put the Sino-Japan gap on a scale of 5 at 4-5, the Sino-South Korean gap at 3, and the Japan-South Korean gap at 2. On the temporal dimension, China's gap with Japan has widened to 5, reflecting all periods of history, while its gap with South Korea has rapidly widened to 4, about the same level as the serious Japan-South Korea gap, which for a time had seemed to narrow to 3. On the sectoral dimension, the cultural divide has widened sharply at the same time as the economic divide has also begun to widen, as has the political divide. The composite for this dimension is 3 for China with its two neighbors and 2 with signs, at least until 2012, of more narrowing between Japan and South Korea. The vertical dimension measures how states view each other's internal system and also shows an estimated gap between China and Japan of 3 as opposed to the Sino-South Korea gap of 2-3, and a narrow Japan-South Korea gap of just 1, although this may have widened in 2013 due to Korean anger over the new Abe cabinet. The horizontal dimension focuses on how identity reflects perceptions of international relations-the international community, the role of the United States, and Asian regionalism. While the Japan-South Korea gap is estimated at 1-2, the Sino-South Korea gap is 3, and the Sino-Japan gap had risen abruptly to 4 in 2010 and may be 5 in 2013. These are preliminary figures based on a broad sample of publications from each country.

Questions can be raised about whether the chosen dimensions are ideal for analysis of national identity and identity gaps. Estimates may be recalculated and extended in time with more precise criteria for content analysis and other methods. The value of the framework that is introduced does not depend on whether results are precise. Instead, it rests on recognition that analysis of international relations in East Asia, and presumably elsewhere, takes bilateral relations as the building blocks and benefits greatly from interpreting them through a prism of mutual perceptions, which are steeped in the national identities of the two states. Often an asymmetry is seen in how the two sides assess the gap between them, as one side strives to widen it while the other may actually prefer to narrow it. Eventually, however, the impact of one side's demonization spreads to the other, as reflected in more threatening actions and growing awareness of tense relations. Such has been the case in China's snub of South Korean goodwill from 2004, especially from 2008, then of Japan's "friendship mode" in 2005, intensifying sharply from 2010, and finally of U.S. efforts to improve relations, ostensibly welcomed to 2008 and then spurned. Coverage is most intense for the way China's national identity influences gaps with the others.

Analyses in Ch. 6 on international relations studies and Ch. 8 on the Sino-U.S. civilizational gap focus attention on how to approach the widening identity gap at a time of increasingly strained bilateral relations. Ch. 6 draws on the evidence in the book to suggest ways to redirect social science scholarship. Assumptions in theory, whether grounded in realism or liberalism, have left East Asian national identities and their impact on the sidelines. U.S. reasoning on convergence in identities and outlooks toward the international system has fallen short. Chinese reasoning on national identity gaps requires considerable rethinking. The essence of Chinese gap widening is not socialism vs. capitalism or authoritarianism vs. democracy, but the fundamental division between Chinese and Western civilizations. By interpreting Confucianism and communism as overlapping manifestations of one civilization (socialism with Chinese characteristics was gradually clarified over thirty years), Chinese have set the terms for rejecting any hint of convergence and establishing an unbridgeable divide, manifested as a dichotomy on all dimensions of identity.

The implications of this analysis for U.S. foreign policy in East Asia are lately becoming clear. With the deepening tensions between Japan and South Korea in late 2012, realization of a triangular security framework no longer can appear possible without policies to diminish their identity gap. Increased urgency in responding to Sino-Japanese tensions and vacillating Sino-South Korean coordination over North Korea also puts a premium on recognizing the impact of their national identity gaps. Finally, policy proposals for managing Sino-U.S. relations narrowly centered on the problem at hand are put in doubt by an awareness of the national identity gap that shapes the responses of both states. It behooves foreign policy specialists to study China more closely to understand this background while also recognizing the value of analysis of changing national identity gaps as a tool in the study of international relations. The starting point for this study is familiarity with the discussions in one country about another on many dimensions, not just their immediate policy steps.