Successful foreign policy combines high principle with smart, timely execution. Tuesday’s visit to show solidarity with Taiwan by House Speaker Nancy Pelosi (D-Calif.) demonstrated the former — but not the latter. The foreseeable reaction from China, which considers Taiwan a wayward province, is underway — including the announcement of provocative naval live-fire exercises in the island’s territorial waters after Ms. Pelosi’s visit ends. President Biden must limit the short-term damage and counter a likely increase in long-term Chinese pressure on Taiwan.