The American-Japanese security relationship has been the cornerstone of US strategy in East Asia for more than half a century. The Obama administration’s “pivot to Asia,” a multipronged effort to keep the United States active in Asian affairs, depends on keeping that relationship strong. Yet while the two countries are investing considerable effort in strengthening ties, there are signs of growing strain. Left unattended, there is a serious and growing risk of a crisis and even a rupture.

Take the “2+2” meeting held in Tokyo last October, where the two governments began revising the guidelines governing defense cooperation between their military forces. They made progress in underlining their continued solidarity and work toward a closer cooperation to meet new security threats: a nuclear-armed North Korea and a more assertive China. But ambivalence was clear.

While Japan may move toward removing some of the legal barriers to closer cooperation, it wants to avoid becoming too entangled in broader US strategic designs. For its part, the United States offered only lukewarm support on the disputed Senkaku-Diaoyu Islands, which are under Japanese control, but are claimed by China. The US reaffirmed orally that if the islands were attacked, it was bound by the terms of its alliance with Japan to come to its aid, but declined to do so in writing, to the disappointment of some in Tokyo.

Past disputes between the United States and Japan didn’t negate the sense that their strategic interests were in substantial agreement. This time, that is being questioned. North Korean nuclear armament and China’s rise have led to a much higher level of threat perception on the part of the Japanese public than at any point since the end of World War II. Although the Soviet Union had far greater military capabilities, the possibility that Japan would be directly threatened seemed remote. Today’s repeated outbreaks of virulent anti-Japanese sentiments—including riots and mass demonstrations—in Beijing and Pyongyang, even in fellow US ally Seoul, has convinced many Japanese that in the event of a conflict, their closest neighbors are capable and eager to attack them. The Chinese-Japanese standoff over the uninhabited Senkaku-Diaoyu Islands and a less militarized dispute with South Korea over the Dokdo-Takeshima Islands reinforce Japanese fears.

This growing sense of threat has encouraged the reemergence of strongly nationalist political leaders, including Japanese Prime Minister Shinzo Abe, who holds revisionist views on Japan’s World War II-era atrocities that are profoundly offensive to Japan’s Asian neighbors. In a potentially vicious cycle, Japan’s resurgent conservative nationalism alarms its neighbors and feeds anti-Japanese sentiments, leading to a greater sense of threat in Japan and a greater readiness to support nationalist politicians. Washington views this with a mixture of trepidation and despair. It seems inconceivable, given the high level of economic interdependence between Japan and its neighbors and the limited strategic value of the disputed territories, that Japan and China would risk a conflict. Yet political realities in Tokyo and Beijing (and Seoul) have locked the sides into a belligerent stance on the disputed islands that sooner or later could lead to a disastrous conflict.

Washington bears some blame for its tensions with Japan. Its position on the territorial disputes is that such disputes be handled peacefully, according to international law. This legalistic position raises suspicions on all sides. Beijing suspects that the United States is trying to encourage the dispute to more firmly embed Japan into an anti-Chinese coalition. In Tokyo, our refusal to commit more fully raises doubts about our reliability in a crisis.

The United States may judge it has little choice but to carry on with its current policies. Revising Japan-US defense cooperation guidelines sends a strong message to Beijing that aggression is intolerable. It reassures the Japanese that the United States will stand by them in a crunch and may discourage Abe from taking a harder-line stance. At the same time, by not taking a position on the territorial issues, Washington warns Japan that its support should not be interpreted as a carte blanche to be more aggressive about history or other sensitive issues, and leaves open the possibility for constructive dialogue with Beijing.

This delicate balancing act will become increasingly impossible to pull off over time. There is little evidence that China will relent on the Senkaku-Diaoyu dispute. It is sending or increasing planes, ships, and unmanned drones into the region, rebuffing Japanese diplomatic feelers. Without stronger US reassurance, Japan will consider responses such as allowing its coast guard to fire warning shots at Chinese ships, stationing police or military personnel on the islands, and even shooting down unmanned drones.

The United States must show stronger support for Tokyo, including written assurances of our backing in a crisis, intensified discussions of US-Japanese military cooperation in the event of a clash in the East China Seas, and even publicly raising that most sensitive of issues: strengthening the US strategic deterrent in the region. The United States also must push Japan to negotiate in earnest with its neighbors over compensating victims of Japanese wartime policies, beginning with the surviving Korean “comfort women” (made sex slaves for the Japanese army) and their families.

Absent this dual-track approach, Obama’s pivot, and eventually the entire US Pacific position, will be in peril.

Thomas U. Berger is a College of Arts & Sciences associate professor of international relations and the author of War, Guilt and World Politics after World War II (Cambridge University Press, 2012). He can be reached at tuberger@bu.edu.

“POV” is an opinion page that provides timely commentaries from students, faculty, and staff on a variety of issues: on-campus, local, state, national, or international. Anyone interested in submitting a piece, which should be about 700 words long, should contact Rich Barlow at barlowr@bu.edu.