Considerable attention has focused on the rising tensions between Japan and China, with some experts now warning that we should not underestimate the possibility of war between the region’s two major powers. Relations between Tokyo and Beijing have certainly become hostile over the past year or so. The ongoing, highly emotional dispute over the Diaoyu/Senkaku Islands in the East China Sea has been the principal source of friction, but Japanese Prime Minister Shinzo Abe’s late December 2013 visit to the Yasukuni Shrine, which contains the remains of 14 high-level, World War II war criminals, also infuriated the Chinese.

Washington is understandably concerned about the deterioration of Sino-Japanese relations, but the surging animosity between those two countries is not the only source of worry for U.S. policy makers. Although it has received less attention, relations between Japan and South Korea are also on an ominous trajectory. The reaction in South Korea to Abe’s pilgrimage to Yasukuni was as angry as the response in China. Seoul also has its own territorial disputes with Tokyo, primarily over a chain of small islands called Dokdo in Korea and Takeshima in Japan, and those controversies are intensifying.

All of this might be a matter of limited concern to the United States if it were not for Washington’s defense treaties with Japan and South Korea. U.S. leaders have already taken the dubious step of insisting that the bilateral defense pact with Tokyo applies not only to indisputable Japanese territory but also to the highly contested Diaoyu/Senkaku Islands. That stance has drawn sharp objections from Beijing and puts the United States on the front lines of a worsening confrontation between China and Japan.

Although an armed conflict between Tokyo and Seoul is less likely than a Sino-Japanese war, Washington’s defense obligations put the United States in an extremely awkward position if the Japanese-Korean relationship crumbles. Clearly, Washington would not be able to honor its obligations to both parties, if they came to blows. One wag suggested that the U.S. Army could fight alongside the Koreans, while the U.S. Marines (based mainly on Okinawa) could assist the Japanese.

It’s no laughing matter, though, and the current tensions underscore the pitfalls of Washington’s tendency to acquire allies or security clients in a promiscuous manner. At a minimum, such ties cause diplomatic headaches; at worst, they can entangle the United States in unwanted, even irrelevant, conflicts. It’s not a new problem. During the Cold War, Washington repeatedly found itself trying to keep NATO allies Greece and Turkey from going to war against each other.

That history, along with the current turmoil in East Asia, should cause U.S. leaders to conduct a thorough re-assessment of the country’s overgrown alliance commitments. Alliances are supposed to advance America’s interests and enhance its security, not drag this country into unnecessary, dangerous quarrels.