But this China-Japan-U.S. tacit entente is under threat amidst the rocky barrenness of the Senkakus. Like two champion footballers arguing over a pair of boots, Japan and China snarl and escalate. Japan points out the United States included the islands in the Okinawa Reversion of 1971. China says the islands have been Chinese since the Ming Dynasty (1368-1644).

True, this is Japan’s dispute, not the United States’, but the two countries together face a broad challenge from China. Ronald Reagan at first felt neutral about the Falkland Islands dispute between Britain and Argentina in 1982, irritating Margaret Thatcher, but in the end he backed Britain for the sake of the alliance.

The real problem in the East China Sea is Japan’s apprehension about China’s growing muscle-power, and China’s maritime push to match economic success with military dominance in its “historical backyard.” An eye on resources, yes, but President Hu Jintao’s remark on the 60th birthday of the People’s Republic of China is seminal: “Today a socialist China is standing toweringly in the Eastern world.”…

Yet Obama just asks everyone to be careful with their guns. His national security aide Daniel Russel briefed the press: “Sino-Japan relations have a significant impact on all of us, and on all the countries in the region, so it’s something we pay close attention to.” But U.S.-Japan relations should also have an impact around the world. Why be passive about the alliance? Why not secure Beijing’s “close attention” too? Must others always lead? It did not help that Hu got a state dinner from Obama whereas Abe got lunch and that Abe’s wife did not make the U.S. trip because Michelle Obama was “too busy” to host her.