US Secretary of State Antony Blinken on Friday condemned China's military drills encircling Taiwan as "a significant escalation".
Blinken said there was "no justification" for the exercises launched by Beijing in response to a visit to Taiwan by US House Speaker Nancy Pelosi.
China fired ballistic missiles and deployed fighter jets and warships around Taiwan, declaring multiple no-go danger zones in some of the busiest shipping lanes in the world.
"These provocative actions are a significant escalation," Blinken said after talks with Southeast Asian foreign ministers in Phnom Penh.
Blinken said this week's stand-off was Beijing's latest attempt to alter the fragile status quo over self-ruled Taiwan, which China's ruling Communist Party regards as part of its territory to be recovered, by force if necessary.
He said he had warned Wang Yi at a recent meeting in Indonesia that Pelosi -- the highest-ranking elected US official to visit Taiwan in 25 years -- would likely make the trip to the island.
"We anticipated that China might take steps like this -- in fact we described this exact scenario," Blinken said.
"The fact is, the speaker's visit was peaceful. There is no justification for this extreme, disproportionate and escalatory military response."
He said the United States' position on Taiwan had not changed and it would "not be provoked" by China's actions.Beijing has insisted its war games are a "necessary" response to Pelosi's visit.