An Asian security standoff.

• Author: Dupont, Alan

Pivotal moments in history are seldom anticipated. And when change is systemic, this rule is even truer. There are unmistakable signs in East Asia, however, that the old, U.S.-dominated order can no longer be sustained in the face of Chinas emerging challenge and the relative weakness of both the United States and Japan. A failure of American diplomacy to adjust to these new power realities, or of China to accommodate long-standing U.S. and Japanese interests, could jeopardize the promise of the much-heralded Asian century and return East Asia to its bloody and fractious past. What emerges in this critical region will have global consequences. As the locus of economic and military power shifts decisively from the Atlantic to the Pacific, it is clear that East Asia has never been so centrally important to the international order. Never before have the world's three preeminent states--the United States, Japan and China--all been Asia-Pacific powers. This raises the stakes for everyone should the Old Order fail precipitously.

For nearly seven decades, this order has been underpinned by U.S. economic and military strength, dating back to the defeat of Japan at the end of World War II and reinforced forty-five years later by the collapse of the Soviet Union. During the Cold War, American preeminence in East Asia was vitiated by both the illusion and reality of Soviet military power. Thereafter, for a brief "unipolar moment," the United States seemed able to do as it pleased without worrying about peer competitors or balancing coalitions. In retrospect, President George W. Bush's first term may be seen as the apogee of Pax Americana. Since then, it has been mostly downhill for a United States weakened by ten years of war, a gridlocked political system and the lingering contagion from the 2008 global financial crisis. President Obama's pivot to Asia, and his attempt to quarantine the region from defense-budget cuts, cannot disguise the sober reality that the U.S. capacity to shape East Asia is no longer what it was.

Once seen as the reliable northern anchor of the U.S. alliance system in East Asia and lauded for its dependability and dynamism, Japan's two-decade political and economic malaise is a significant cause of the weakening of the Old Order. The near meltdown of the tsunami-crippled Fukushima nuclear-power plant in 2011 can be seen as a metaphor for the corrosion of Japan's increasingly inward-looking body politic. The country lacks confidence and is beset by a host of domestic problems. Leadership stasis has made it difficult for the United States to reinvigorate the strategic partnership with Japan or to be sure where the country is heading. This is reflected in the failure to reach agreement on the relocation of the important Marine base on Okinawa. While Japan remains a major economy, its gross domestic product has not grown for twenty years, and the country suffered the indignity of being overtaken by China as the world's second-largest economy in 2011. Aging and shrinking demographically, Japan faces the prospect of being consigned to the second rank of East Asia's middle powers unless it can recapture its lost elan and purpose.

But China's rise is the main reason for the loss of Washington's once-unrivaled ability to influence the region's affairs. With a population of 1.4 billion, more than the rest of East Asia and the United States combined, China is a megastate that for millennia was the dominant polity in Asia and now makes little secret of its desire to reclaim its former status. These dreams are no longer illusory, for modern China has the strategic clout to realize them. Its population and economy dwarf those of Fascist Germany, Imperial Japan and the Soviet Union--previous and ultimately vanquished challengers of U.S. power. China's reemergence poses strategic challenges of a complexity and magnitude not previously experienced by the United States, or the rest of East Asia, for that matter. The principal unknown is the path Chinas leaders will follow, often posed in overly stark and simplistic terms as a choice between responsible stakeholder or revisionist state. In fact, China is likely to be both, conforming to the norms of the international system except when its core interests conflict with those norms.

While long anticipated--indeed, U.S. policy planners were warning of these strategic implications as far...