"Serious concern" for US "Taiwan siege drill""You have to show your self-control".

The U.S. has expressed serious concern and urged Chinese troops to show restraint in their siege drills in Taiwan.

"China's response to routine annual speeches with military provocations is unjust and escalates the risk," State Department spokesman Matthew Miller said in a statement.

"We urge China to show restraint and not to take additional actions that may undermine peace and stability in the Taiwan Strait and the wider region," he said.

It also added that the U.S. has maintained its "One China" policy for a long time under the "Taiwan Relations Act."

Apart from the "One China" principle, the U.S. has enacted a "Taiwan Relations Act" that includes providing defensive weapons and allowing high-ranking officials to visit the U.S. to effectively support Taiwan.