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The recent U.S. decision to upgrade Taiwan's existing fleet of F-16 fighter aircraft—taken in response to China's growing military threat to the island—has triggered a repeat of what most observers regard as a troublesome but ultimately manageable dynamic: Washington sells arms, Beijing blusters and threatens, the bilateral relationship suffers some disruption, and then everything returns to business as usual across the Taiwan Strait. But this kind of business as usual could lead to a major crisis with China.

In the existing dynamic, Washington sees itself as a stabilizer, encouraging cross-strait dialogue, cautioning both sides that it will oppose any unilateral actions that might threaten the peace and deterring Beijing by maintaining its military...