For decades, when U.S. policymakers contemplated conflict with China, their fears focused on Taiwan. Today, by contrast, Sino-American tensions seem to be on the rise everywhere, while relations between Taiwan and the mainland have significantly improved.

Since Taiwanese President Ma Ying-jeou took office in 2008, the government in Taipei has inked 18 agreements with China, unleashing a surge of commerce and tourism. With trade barriers falling and direct flights proliferating — there are more than 600 a week, up from none five years ago — the Taiwan Strait is the only flash point in Asia where globalization and economic integration seem to be trumping historical antagonisms.

This island of 23 million stands out from the rest of the region in another respect: While the Obama administration has been deepening U.S. alliances across Asia, Taiwan has been conspicuous for its absence from that conversation. In a lengthy address this spring describing the future of the U.S. "rebalance" toward Asia, national security adviser Tom Donilon didn't mention Taiwan once. Nor have other senior officials in major speeches about the region.