Sign at the U.S. Marine Corps' Camp Schwab in Okinawa, JapanSince World War II, the peace of East Asia has largely been kept by the very conspicuous presence of American military power. American power keeps a lot of corks in a lot of bottles in this part of the world. An insufficiently strong U.S. presence would unleash old demons that currently lie dormant and facilitate destructive security dilemmas. The short-term costs the United States incurs with its current Asian presence would be dwarfed by catastrophic long-term costs should the U.S. footprint be diminished.

The potential paths to conflict in East Asia are numerous, but here are the most salient.

China and Taiwan

In 1662, as Manchu warriors sought to consolidate the new Qing dynasty in Beijing, remnants of the previous dynasty, the Ming, fled to the remote island of Taiwan. Under their leadership, Taiwan governed itself as the autonomous “Kingdom of Tungning” and plotted how best to undermine the mainland. It was not until 1683 that Tungning was finally conquered by the Qing Emperor Kangxi and incorporated into the empire.

The Ming’s final redoubt should shine some light on modern China’s strange obsession with Taiwan. There is little else to explain it. The small, barren island has few natural resources to speak of, and there is little further benefit China would acquire from direct sovereignty that it does not already get through trade and treaties. China would lose much and gain little from a war with Taiwan and yet even now, three Taiwan Strait crises later, war is still not entirely implausible. The Taiwan conundrum falls into the especially murky and dangerous realm of national pride, removing it from practical consideration. Since Chiang Kai-Shek fled there in 1949, it has remained a nettlesome thorn preventing the communists in Beijing from being able to claim a complete victory for their revolution.

China’s military-industrial complex poses a unique challenge as well. With weak civilian institutions, China’s skittish leaders constantly fret about the loyalty of their military, the People’s Liberation Army (PLA). A 10 percent average annual increase for the last decade has kept the Leviathan fed and sated, but Taiwan is another matter entirely.

China’s generals have been frothing at the mouth for Taiwan for decades and have never been comfortable with the more conciliatory policies toward the island pursued by Hu Jintao and his more moderate administration. The fait accompli of U.S. military power is the primary reason that civilian leadership has managed to prevail over the more ribald currents of nationalism for all these years. If America exits the scene and withdraws military and political support for Taiwan, pressure from the PLA for more assertive action would be enormous. Without the counterargument of robust U.S. deterrent, it will become more difficult for cooler heads to prevail.

Japanese Remilitarization

As America looks to scale back its international commitments, many in the West see the idea of a remilitarized Japan as long overdue. Japan has come a long way from the ashes of 1945 and might now throw off the shackles of its pacifist WWII constitution and assume responsibility for its own defense.

But this view does not take into account the perspectives of Japan’s neighbors. Japanese atrocities on the Asian mainland were far beyond anything Americans experienced at Pearl Harbor. The eminent historian Chalmers Johnson estimated that the Japanese army left 30 million dead in Asia, 23 million of whom were ethnic Chinese. (For a more personal account, Iris Chang’s succinct and searing work The Rape of Nanking provides a snapshot into a holocaust equivalent to that perpetrated by Hitler.)

While Germany has spent the last sixty years in abject apology, criminalizing holocaust denial and shunning even the faintest whiff of nationalism, Japan has been more taciturn in acknowledging former atrocities. Academics, lay people and even former prime minister Shinzo Abe have at different times either denied all or some of Japan’s war crimes. Abe and his predecessor Junichiro Koizumi made repeated visits to a shrine that honors Japanese war dead going back to the mid-nineteenth century and also includes a number of Japan’s most heinous war criminals.

This history of atrocities keeps Japan’s neighbors on edge. Though China now has the largest military in the world, nuclear weapons and the second-largest economy, fear and distrust of Japan is primal. Though the idea of a resurgent Japanese threat to Asia may be laughable in the West, it is very real in Beijing—and this paranoia should not be dismissed so blithely. In the East, it has long been an article of faith that the U.S. security umbrella keeps a lid on Japanese militarism.

When Xi Jinping calls for an American role in East Asia, his sentiments seem genuine. If American soldiers were to leave Japan, or the Japanese-American security treaty were allowed to expire, the Japanese would likely reconstitute their military: exactly what Washington hopes for and Beijing dreads. Withdrawal of U.S. protection would lead to the emergence of a classic security dilemma, with Japan racing to narrow a glaring imbalance of capabilities with China.

Despite good relations under Mao and Deng, Sino-Japanese friendship took a precipitous turn after the Tiananmen Square Massacre. Since 1989, China has focused on “patriotic education” as a way of taking attention off the domestic issues that sparked Tiananmen. Much of that education involved reviving nationalist, anti-Japanese sentiment and dutifully reminding Chinese citizens of past atrocities with a number of annual public remembrances.

A military buildup by the Japanese would strike a deep nerve in China and would spur even greater hostility on the mainland. A number of Japan’s regional neighbors still smarting from their own World War II experiences also would likely view a Japanese buildup with hostility. With deft diplomacy, China could position itself as a regional savior. Always looking to strengthen its soft power bona fides, Beijing would be all too happy to strike security arrangements with the countries Washington leaves out in the cold.

The Koreas

For the United States, the Korean War ended in 1953. But in Pyongyang, the struggle continues to this day. The West would be wise to remember that a formal peace accord was never signed and the conflict has technically been ongoing for 60 years. For U.S. soldiers stationed in South Korea, there is always the perennial possibility of a resumption of hostilities. Yet despite North Korean bluster and brinkmanship, most recently with the shelling of Yeonpyeong Island, the North has been reticent about going further. So far, their bark has been worse than their bite.

It would be a mistake to assume North Korean leaders are irrational. All the Kim dynasty wants is security. Their pursuit of nuclear weapons was a response to a justified fear of U.S. intervention, especially after being included in George W. Bush’s Axis of Evil. Even North Korea’s most bellicose know that given the current level of U.S. deterrent, prodding South Korea into war would be suicide.

But if U.S. soldiers went home as part of a larger Asian retreat, North Koreans could reevaluate their options. With an outsize view of their own capabilities, there would be more pressure to finish the job—or, at the very least, to use the new leverage to step up harassment of their southern neighbor. Beijing would likely choke off the North before it could cause too much trouble (and disrupt China’s lucrative trade with South Korea), but it would force China into an awkward position: protecting the sworn enemy of their closest ally from aggression by that ally. It would be a recipe for instability.

My students at Tsinghua University often ask how America came to “control the world.” I tell them that U.S. power and influence was not something the country came to willingly but a burden taken on reluctantly from a Europe that surrendered its global hegemony because—in simple terms—the Western powers could not get along with each other.

As U.S. hegemony continues to wane, Washington will have neither the means nor the will to provide security for multiple regions. But three of the four rising regional powers known as the BRICs—Brazil, Russia, India and China—are in Asia and will likely form the focal points of an overall power shift to the East in the next century. As U.S. interests follow suit, a drawdown in Asia would be insanity.

Jonathan Levine is a lecturer of American Studies and English at Tsinghua University in Beijing. You can follow him on Twitter @LevineJonathan

Image: Ojo de Cineasta