(NewsNation) — President Joe Biden said in an interview that aired Sunday that U.S. military forces would defend Taiwan if the island nation were invaded by China.

The president’s comments to CBS’s “60 Minutes” come at a time of escalating tension between China and Taiwan following a visit by U.S. House Speaker Nancy Pelosi to Taiwan in August that angered Beijing.

In the interview, Biden said the U.S. is still adhering to the “One China” policy, which acknowledges China’s position that there is only one legitimate Chinese government, based in Beijing, and that Taiwan is part of China. But the U.S. maintains “strategic ambiguity” about whether it would defend Taiwan militarily.

When asked by “60 Minutes” correspondent Scott Pelley if the U.S. would defend the island, Biden responded: “Yes, if in fact there was an unprecedented attack.”

A White House official told CBS News after the interview that the U.S. official position of “strategic ambiguity” has not changed.

Following Pelosi’s visit to the island, China held a series of military drills, including the largest ever in the Taiwan Strait. Taiwan responded with drills of its own, showcasing its fighter jets.

Multiple congressional delegations have visited Taiwan since Pelosi, and a U.S. Senate committee recently approved a bill that could significantly increase American defense support for Taiwan. China slammed the bill, saying it violates the One China policy.

Washington is obligated by federal law to see that Taiwan has the means to defend itself but doesn’t say whether U.S. forces would be sent. The United States has no formal relations with the island but maintains informal diplomatic ties.

Taiwan’s foreign ministry on Monday expressed “sincere gratitude” to Biden for “affirming the U.S. government’s rock-solid promise of security to Taiwan.”

Taiwan will “resist authoritarian expansion and aggression” and “deepen the close security partnership” with Washington and other governments “with similar thinking” to protect regional stability, the statement said.

Taiwan and China split in 1949 after a civil war that ended with the Communist Party in control of the mainland. The two governments say they are one country but dispute which is entitled to be the national leader.

The Associated Press contributed to this report.