China sent 33 military aircraft around Taiwan over a 24-hour period, the Defense Ministry in Taipei said Saturday, the most since the democratic island elected a new president less than two weeks ago.

The ministry said 13 of the aircraft, which it did not identify, had crossed the median line of the Taiwan Strait that once served as an unofficial boundary between the two sides. Seven navy vessels were also spotted operating around the island, while the ministry also said it had detected two Chinese balloons crossing the strait.

Taiwan's military "monitored the situation ... and employed aircraft, Navy vessels, and coastal missile systems in response to the detected activities,” the ministry said.

Taiwanese voters elected current Vice President Lai Ching-te to succeed Tsai Ing-wen as the country’s leader in a poll lambasted by China, with officials in Beijing labeling Lai “a destroyer of peace across the Taiwan Strait.”

China claims Taiwan as a renegade province that must be united with the mainland, by force if necessary. This policy has triggered concerns of a possible invasion by China, despite hints by U.S. President Joe Biden that Washington would help Taiwan militarily in the event of a conflict.

On Saturday, Taiwan was expected to be on the agenda for high-level talks between U.S. national security adviser Jake Sullivan and Chinese Foreign Minister Wang Yi in Bangkok. The two officials were looking to follow through on a promise made by Biden and Chinese leader Xi Jinping to improve dialogue, during their summit in San Francisco in November.

During the talks, which kicked off Friday, Wang was set to “state China’s position on issues such as China-U.S. relations and the Taiwan question and exchange views with the U.S. on international and regional issues of mutual interest,” Chinese Foreign Ministry spokesman Wang Wenbin told a briefing.

Beijing has in recent years regularized what it says are patrols and combat exercises around Taiwan, part of a sustained pressure campaign that has also had a diplomatic angle.

Just two days after the election, China lured away one of the handful of countries that formally recognize Taiwan, poaching the Pacific Island nation of Nauru, which severed ties with Taipei. The move left Taiwan with just 12 diplomatic allies — a number that could be further whittled down after the pro-Taipei leader of the Pacific Island nation of Tuvalu lost an election Saturday.