TOKYO (AP) — President Joe Biden said Monday that the U.S. would intervene militarily if China were to invade Taiwan, saying the burden to protect Taiwan is “even stronger’ after Russia’s invasion of Ukraine. It was one of the most forceful presidential statements in support of self-governing in decades. Biden, at a news conference in Tokyo, said “yes” when asked if he was willing to get involved militarily to defend Taiwan if China invaded. “That’s the commitment we made,” he added.

The U.S. traditionally has avoided making such an explicit security guarantee to Taiwan, with which it no longer has a mutual defense treaty, instead maintaining a policy of “strategic ambiguity” about how far it would be willing to go if China invaded. The 1979 Taiwan Relations Act, which has governed U.S. relations with the island, does not require the U.S. to step in militarily to defend Taiwan if China invades, but makes it American policy to ensure Taiwan has the resources to defend itself and to prevent any unilateral change of status in Taiwan by Beijing.

Biden’s comments drew a sharp response from the mainland, which has claimed Taiwan to be a rogue province. Chinese Foreign Ministry spokesperson Wang Wenbin expressed “strong dissatisfaction and resolute opposition” to Biden’s comments. “China has no room for compromise or concessions on issues involving China’s core interests such as sovereignty and territorial integrity.”

He added, “China will take firm action to safeguard its sovereignty and security interests, and we will do what we say.”