China Sends Record Number of Warplanes Across Key Boundary Line With Taiwan

China sent a record number of warplanes across a U.S.-drawn boundary in the Taiwan Strait—a move that comes as the new president of the archipelago mulls a trip that may include a stop in America.

Some 56 aircraft crossed the so-called median line as of early Thursday, the Ministry of National Defense in Taipei said on the X social media site. Taiwanese aircraft, naval vessels and missile systems were used “in response” to the flights by the People’s Liberation Army, the military added, without providing details on what that entailed.

The archipelago’s armed forces have “a close grasp of the dynamics of the sea and airspace surrounding the Taiwan Strait, including the actions of the PLA aircraft and ships,” ministry spokesperson Sun Li-fang told reporters later in the day.

Taiwan President Lai Ching-te was considering passing through the U.S. while potentially visiting nations that have ties with the archipelago, Foreign Minister Lin Chia-lung said Wednesday, according to the semi-official Central News Agency in Taipei. Details of the trip were still being planned, Lin added.

Beijing reacted to a similar stop in the U.S. by Lai’s predecessor, Tsai Ing-wen, last year by holding large military exercises. Tsai met then-House Speaker Kevin McCarthy, a move that angered Beijing, which opposes nations it has ties with from having official contact with Taiwan.

The latest warplane flights add to the pressure campaign China has rolled out since the election victory in January of Lai, who Beijing accuses of pursuing independence. That drive has included holding major military drills just after he took office in May, peeling off one of Taiwan’s few remaining diplomatic allies and expanding a law targeting what it sees as “separatists.”

China has vowed to bring the archipelago of 23 million people under its control someday, by force if necessary. 

Read More: TIME’s Exclusive Interview With Taiwan President Lai Ching-te

When asked about the warplanes crossing the median line at a regular press briefing in Beijing, Foreign Ministry spokesman Lin Jian avoided directly responding. “The determination of China to safeguard its sovereignty and territorial integrity remains unrelenting,” he said.

While Beijing has never officially recognized the median line that the U.S. drew in 1954 during a period of cross-strait tensions, its military had for decades respected the boundary.

The PLA has stepped up incursions across the demarcation in recent years, effectively shrinking the buffer zone between the two sides and slashing the amount of time that Taiwan’s smaller military has to react to any attack from China.

President Joe Biden has repeatedly said the U.S. would come to Taiwan’s aid in the event of a Chinese invasion. The U.S. has also stepped up military aid to the archipelago that produces the bulk of the world’s advanced semiconductors in recent years in the hopes of deterring any attack.