Taiwan's Vice President William Lai flies to the United States on Saturday in a sensitive trip that has angered Chinese officials.
The democratic island is claimed by China, which has vowed to take the territory one day -- by force, if necessary -- and has ramped up political and military pressure.
It opposes other countries' official exchanges with Taiwan, and often reacts angrily to Taiwanese leaders' stopovers in the United States.
Lai -- a candidate for Taiwan's presidential elections next year -- is officially making only transit stops in the United States en route to and from Paraguay, where he will be attending the inauguration.
"Departing soon for #Asuncion to attend (president-elect Santiago Pena's) inauguration & convey to him & the people of #Paraguay the best wishes of (Taiwan)," Lai wrote on Twitter, now called X.
"(E)xcited to meet with #US friends in transit."
In response, Laura Rosenberger, chair of the American Institute in Taiwan -- a de-facto embassy for Taiwan based in Virginia -- wrote that officials were "looking forward to welcoming" Lai.
Lai is expected to stop in New York en route to Paraguay, and San Francisco when flying back.
Last week, China's foreign ministry urged US leaders to "abide by the One-China principle and... to stop official exchanges between the US and Taiwan".
In April, China staged three days of military exercises simulating a blockade of Taiwan after President Tsai Ing-wen met US House Speaker Kevin McCarthy in California.
Ahead of Lai's departure, Taiwan had sought to downplay the trip, with foreign ministry spokesman Jeff Liu saying there was "nothing special" about vice presidents transiting in the United States -- which has occurred 11 times before.
"China has no reason to overreact or take the opportunity to escalate the situation," Liu said in a briefing this week, adding that Lai was making the trip in his capacity as vice president, not as a presidential candidate.
"If China decides... to take provocative actions, it is China, not Taiwan or the United States, that undermines the status quo of peace and stability in the region," Liu said.
In the week leading up to Lai's departure, incursions by the Chinese military around Taiwan's waters and airspace -- which have been happening near-daily in the past year -- were larger than usual.
On Wednesday, the defence ministry said 33 Chinese warplanes and six vessels were detected around the island over the past 24 hours.
