"While our policy has not changed, what has changed is Beijing's growing coercion," Blinken said in a wide-ranging speech on China.

He pointed to Beijing's attempts to "cut off Taiwan's relations with countries around the world and blocking it from participating in international organizations."

"And Beijing has engaged in increasingly provocative rhetoric and activity like flying PLA aircraft near Taiwan on an almost daily basis," Blinken said, referring to the People's Liberation Army.

Hailing Taiwan as a "vibrant democracy and leading economy," Blinken said that the United States would pursue its "strong unofficial relationship" including providing arms but reiterated that the United States recognizes only Beijing.

"We oppose any unilateral changes to the status quo from either side, we do not support Taiwan independence and we expect cross-strait differences to be resolved by peaceful means," he said.

Biden appeared to break decades of US policy on a weekend visit to Japan by saying in response to a question that the United States would defend Taiwan militarily if it is attacked by China.

He later insisted there was no change in the US stance of "strategic ambiguity" on whether Washington would intervene more directly than providing weapons to Taiwan.

China claims Taiwan, where the mainland's nationalists fled in 1949 after losing the civil war to the communists, to be a province awaiting reunification, by force if necessary.

The United States switched recognition from Taipei to Beijing in 1979.