China's rift with Japan is open challenge to U.S.

As Chinese maritime vessels continue to enter the Senkaku Islands' waters, there is continued focus on the tense state of Sino-Japanese relations.

The Senkakus (Diaoyu in Chinese) themselves are worth little. Even if their petroleum resources turn out to be significant, the gains would be microscopic relative to China's gross domestic product. Their military value is marginal. They have played no role in Chinese history, so they lack symbolic significance.

They are, however, geopolitically important in the context of Sino-American rivalry. The United States treats them de facto as Japanese territory. Because Japan is one of America's few vital allies, provoking Japan over the Senkakus is tantamount to picking a fight with the U.S..