A top Japanese defense official on Friday urged U.S. President-elect Joe Biden to "be strong" in supporting Taiwan in the face of an aggressive China, calling the island's safety a "red line."

"We are concerned China will expand its aggressive stance into areas other than Hong Kong. I think one of the next targets, or what everyone is worried about, is Taiwan," said Yasuhide Nakayama, the state minister for defense.

In an interview, Nakayama urged Biden to take a similar line on Taiwan as outgoing President Donald Trump, who has significantly boosted military sales to the Chinese-claimed island and increased engagement.