The Chinese Foreign Ministry criticized Taiwan vice president Lai Ching-te’s visits to the U.S. that bookend a trip now under way to Paraguay, saying the plan "seriously violates the one-China principle.”

"China firmly opposes any form of official interaction between the U.S. and the Taiwan region,” according to a statement Sunday that cited a ministry spokesperson. It also condemned the U.S. decision to arrange the stopovers that it said undermined China’s "sovereignty and territorial integrity.”

Lai’s stopovers in New York and California are scheduled to take place on his way to and from Paraguay for the inauguration of its new president. Lai is also the presidential candidate of Taiwan’s ruling Democratic Progressive Party and the election’s front-runner.

The critique comes amid rising concerns about military conflict in the region, as Taiwan is one of the main flashpoints in U.S.-China ties. The statement called for the U.S. to stop all official interaction with Taiwan and end support for its independence.

"China is closely following the developments of the situation and will take resolute and strong measures to safeguard its sovereignty and territorial integrity,” the Foreign Ministry said.