The Wall Street Journal reported over the weekend that Japan may not help defend Taiwan from a Chinese invasion. From the Journal:

If China moves to seize Taiwan and the U.S. intervenes, as President Biden has said it would, the first response would likely come from those U.S. bases [in Okinawa]. Under an agreement dating from the 1960s, the U.S. would need Japan’s approval—but Tokyo would feel pressure to provide that, as refusing would jeopardize the alliance that ensures its security.

Getting Japan to engage in the fight directly would be harder. Japanese leaders publicly shun discussion of a role in any Taiwan war, in part because public opinion is generally against getting ensnared in a conflict.

Japan’s reticence to commit to the fight is understandable. After all, in a one-on-one confrontation with China, Japan would likely be hopelessly outgunned.

The problem with Japanese noninterventionism is that there’s good reason to believe that China would not stop at Taiwan. The long history of expansionist states offers few examples of those that stopped without being forced to do so. China’s claim on Japan’s Senkaku Islands and its willingness to test ballistic missiles in Japanese waters suggest that it would be all too happy to rule the Land of the Rising Sun.

This is especially true because of those bases from which the American defense of Taiwan would be led. It is not prudent to assume that China would decline to retaliate against those bases, or indeed against Japan more broadly, if Japanese forces do not join the conflict. Without those bases, of course, Japan would be even more exposed to Chinese hegemony.

If China decides to invade Taiwan, as it is preparing to do by the end of the decade, Japan will be forced to make a hard choice. It could, of course, stand back and hope that Xi exercises restraint, as unlikely as that seems. It may well be safer, however, to help the United States beat back China before Japan becomes the primary battleground in the contest for the Pacific.