China’s military flew 38 fighter jets and other warplanes near Taiwan, the Taiwanese defence ministry said on Friday, in the largest such flight display since the large military exercise in which it simulated sealing off the island earlier in the month. Naval vessels were also seen in the area as part of China’s long-running campaign of intimidation against Taiwan

Later Friday, China’s People’s Liberation Army issued a protest over the flight of a US Navy P-8A Poseidon anti-submarine patrol aircraft through the Taiwan Strait separating mainland China from the self-governing island democracy claimed by Beijing.

Calling Thursday’s flight a provocation that the US “openly hyped-up”, the PLA’s Army’s Eastern Theatre Command said it scrambled fighter jets to monitor the plane’s flight.

Such acts “fully prove that the US is a disruptor of peace and stability in the Taiwan Strait and a creator of security risks in the Taiwan Strait”, the statement said.

“Theatre troops maintain a high level of alert at all times and resolutely defend national sovereignty and security as well as regional peace and stability.” The US 7th Fleet said Thursday’s flight was in accordance with international law and “demonstrates the United States’ commitment to a free and open Indo-Pacific”.

 “The United States will continue to fly, sail, and operate anywhere international law allows including within the Taiwan Strait,” the statement said. The US remains Taiwan’s closest military and political ally, despite the lack of formal diplomatic ties between them. US law requires Washington to treat all threats to the island as matters of “grave concern”, though it remains ambiguous over whether American forces would be dispatched to help defend the island.

Beijing threatens to bring Taiwan under its control by force if necessary and intensely nationalistic Chinese leader Xi Jinping has sworn never to give up “a single inch” of territory claimed by his country — a pledge that applies to Taiwan, the disputed border with India and the South China Sea that China claims almost in its entirety.