Crucial test:Taiwanese sailors standing guard in front of a Navy frigate in the port of Keelung, on March 18.APJOHNSON LAI  

The American military is warning that China is probably accelerating its timetable for capturing control of Taiwan, the island democracy that has been the chief source of tension between Washington and Beijing for decades and is widely seen as the most likely trigger for a potentially catastrophic U.S.-China war.

The worry about Taiwan comes as China wields new strength from years of military buildup. It has become more aggressive with Taiwan and more assertive in sovereignty disputes in the South China Sea. Beijing also has become more confrontational with Washington; senior Chinese officials traded sharp and unusually public barbs with Secretary of State Antony Blinken in talks in Alaska last month.

Tough choice

A military move against Taiwan, however, would be a test of U.S. support for the island that Beijing views as a breakaway province. For the Biden administration, it could present the choice of abandoning a friendly, democratic entity or risking what could become an all-out war over a cause that is not on the radar of most Americans. The U.S. has long pledged to help Taiwan defend itself, but it has deliberately left unclear how far it would go in response to a Chinese attack.

This accumulation of concerns meshes with the administration’s view that China is a frontline challenge for the U.S. and that more must be done soon — militarily, diplomatically and by other means — to deter Beijing.

“We have indications that the risks are actually going up,” Adm. Philip Davidson, the most senior U.S. military commander in the Asia-Pacific region, told a Senate panel last month, referring to a Chinese move on Taiwan. “The threat is manifest during this decade — in fact, in the next six years,” he said.

On Wednesday, Taiwanese Foreign Minister Joseph Wu said the military threat against his country is increasing, and while he said it was not yet “particularly alarming,” the Chinese military in the last couple of years has been conducting what he called “real combat-type” exercises closer to the island.