GIVEN PRESIDENT Obama’s preoccupation with ending what he calls “a decade of war,” it’s hard to believe that the United States could be dragged into a military conflict in the western Pacific over a group of tiny, uninhabited islands claimed by both Japan and China. Probably, it won’t be. Yet thanks to a disturbing confluence of events in those countries and Mr. Obama’s own commitments, the chance that it will happen is rising.

The Senkaku Islands, called the Diaoyu by China, have been under Japanese administration since 1895; for decades, China agreed to leave its claim to them on a back burner. But Japan’s nationalizationin September of three of the islets — undertaken in an attempt to head off an attempt by a nationalist politician to gain hold of them — provided China’s military and Communist leadership with a pretext for rabble-rousing.

In recent weeks Beijing’s provocations have escalated from dispatching surveillance ships to the islands to scrambling warplanes in response to Japan’s. China’s state-controlled media have been whipping up something like war fever, with one paper declaring that a military fight is “more likely” and the country “needs to prepare for the worst.” Disturbingly, this provocative and dangerous campaign has been overseen by the new Communist leadership under Xi Jinping, which has ample motive to divert attention from domestic problems.

The political climate in Tokyo, too, gives cause for concern. The new prime minister, Shinzo Abe, is a nationalist who has packed his cabinet with politicians who share his aims of boosting Japanese defense spending and standing up to China. Japan has refused negotiations over the islands, declaring that there is nothing to discuss.

The Obama administration has been trying to defuse the dispute, dispatching a senior State Department official to Tokyo last week to call for “cooler heads to prevail.” But Secretary of State Hillary Rodham Clinton has also reiterated a position the administration first adopted two years ago: A security treaty binding the United States to defend Japan against attack applies to the islets. That public stance may have been intended to deter China from provoking a crisis, but it also magnifies the stakes for Washington. Should China attempt to seize control of the territory, Mr. Obama could have to choose between backing Japan in a military confrontation and a climb-down that would undermine the “pivot to Asia” he has placed at the center of his foreign policy.

Fortunately, there were signs of a cooling-off this week. Mr. Abe dispatched an emissary to Beijing with a letter for Mr. Xi. The Japanese leader, who has been invited to Washington for a meeting with Mr. Obama next month, should be looking for ways to ease tensions without rewarding Beijing’s belligerence. With U.S. help, it ought to be possible to return the issue of the Senkakus to the back burner, where it belongs.