China flew a record number of warplanes around Taiwan, in an apparent show of displeasure over visits by a pair of American officials.

Taiwan said it detected 103 People’s Liberation Army warplanes and nine ships in its vicinity in the 24 hours to early Monday, adding this posed “posed serious challenges to security across the strait and in the region.” The number of aircraft was the most in Bloomberg-compiled data going back three years.

Forty of the planes crossed the median line in the Taiwan Strait, the second time in less than a week that China has sent that many aircraft across the line the US drew in 1954. The sorties wear down Taiwan’s much smaller military and cut the time that it has to react to any attack.

While China usually doesn’t give reasons for conducting military activity around the island of 23 million people it has pledged to someday control, bigger sorties tend to coincide with meetings between foreign and Taiwanese officials. The US has criticized China for holding such exercises, calling them “provocative.”

Arizona Governor Katie Hobbs is leading a delegation that’s visiting until Wednesday, a trip will include a meeting with President Tsai Ing-wen. Hobbs plans to hold talks with top economic and trade officials, and the business community.

Taiwan Semiconductor Manufacturing Co. has said it plans to spend $40 billion to build capacity in Arizona, though in July the chipmaker said production at a planned facility would be postponed from late 2024 until 2025 due to challenges including a shortage of skilled workers and expenses running higher than in Taiwan.

Also visiting the island this week is Laurie Locascio, under secretary of commerce for standards and technology, who met Tsai on Monday. The visit is likely a follow-up to a rare gathering in the US in April when US and Taiwanese security officials discussed how companies from the island could adopt key US defense supply chain standards.

French Senator Olivier Cadic is also traveling to Taiwan, with plans to meet Vice Premier Cheng Wen-tsan and Wellington Koo, secretary-general of the National Security Council.

See: US, Chinese Officials Meet in Malta to Keep Channels Open

In a sign of the prominence Taiwan’s status plays in tensions between the US and China, Chinese Foreign Minister Wang Yi used a meeting in Malta with National Security Adviser Jake Sullivan over the weekend to reiterate that Beijing considers the island a red line in the relationship.

The two sides appeared to have made their usual points on Taiwan, though Sullivan emphasized that the provision of arms or foreign military assistance to Taipei doesn’t mean the US supports Taiwanese independence or views the island as a sovereign nation, according to an administration official.

Last week, China announced it was sanctioning Northrop Grumman Corp. and a subsidiary of Lockheed Martin Corp. for supplying arms to Taiwan. Neither company has any activities to sanction in China so the move is mostly symbolic.

In August, a US agency announced a $500 million sale of equipment for F-16 fighters that will be supplied by Lockheed Martin. The same agency announced in December that Northrop Grumman would supply Taiwan with a system to deploy anti-tank mines.

Taiwan warned last week that China will ratchet up the military pressure it has been applying in recent years, a squeeze that’s largely borne out of frustration that Tsai’s government won’t acknowledge that Taiwan is part of China.

More: Taiwan Warns China Pressure to Rise; PLA Sets Warship Record

Major General Huang Wen-chi said Tuesday that “the PLA pressure will continue and we think the pressure tomorrow will be larger than today.” His comments came just after China sailed 20 warships near the island, another record.

--With assistance from Kari Lindberg.