A furious China launched “punishment” drills around Taiwan on Thursday in what it said was a response to “separatist acts”, sending up heavily armed warplanes and staging mock attacks as state media denounced newly inaugurated President Lai Ching-te.

The exercises, in the Taiwan Strait and around groups of Taiwan-controlled islands beside the Chinese coast, come just three days after Lai took office, a man Beijing detests as a “separatist”.UN Secretary General Antonio Guterres’s spokesman called for all sides to “refrain from acts that could escalate tensions in the region” amid China’s military drills around Taiwan.

“On China, I can tell you that we’re of course following the developments in the Taiwan Straits closely. We urge the relevant parties to refrain from acts that could escalate tensions in the region,” said Stephane Dujarric. The United States “strongly” urged China to show restraint after it launched military drills around Taiwan following the inauguration of a new president, describing Beijing’s actions as “reckless”.

Washington had “noted with concern” and was “closely monitoring” the drills that China said were punishment for Taiwanese Presi­dent Lai Ching-te’s inauguration speech, a senior US official said.

“We strongly urge Beijing to act with restraint,” the Biden administration official said, warning China not to use Taiwan’s political transition as a “pretext or excuse for provocative or coercive measures.” China’s actions were “reckless, risk escalation, and erode longstanding norms that have maintained regional peace and stability for decades,” the official added.

The United States, which recently approved billions in military aid for Taipei, was “confident in our current force posture” in the region. The Chinese drills came after President Lai said in his inaugural speech on Monday that Taiwan “must demonstrate our resolution to defend our nation”.

China, which claims Taiwan as part of its territory, has denounced Lai’s speech as a “confession of independence.” Washington and Beijing have been trying to thaw their relations recently, with President Joe Biden and President Xi Jinping meeting in California last year. However, Taiwan remains a major source of tension.

A senior US general said earlier that the Chinese drills were expected but “concerning”. “We expected something like this, frankly,” US Lieutenant General Stephen Sklenka, the US Indo-Pacific Command deputy commander, told an audience in Canberra. “Just because we expect that behavior does not mean that we should not condemn it — and we need to condemn it publicly,” he said.

“It is concerning.” Sklenka said other nations besides the United States should speak out against the drills.

The Eastern Theatre Command of the Chinese People’s Liberation Army (PLA) said it had started joint military drills, involving the army, navy, air force and rocket force, in areas around Taiwan at 7:45am.

The drills are being held in the Taiwan Strait, the north, south and east of Taiwan, as well as areas around the Taiwan-controlled islands of Kinmen, Matsu, Wuqiu and Dongyin, the command said in a statement, the first time China’s exercises have included areas round these islands.