US lawmakers have arrived in Taiwan just 12 days after House Speaker Nancy Pelosi's visit prompted days of threatening Chinese military drills around the island.
Senator Ed Markey and four others will meet President Tsai Ing-wen, other officials and members of the private sector to discuss shared interests including reducing tensions in the Taiwan Strait.
Beijing responded to Ms Pelosi's visit on 2 August by sending missiles, warships and warplanes into the seas and skies around Taiwan for several days afterwards.
Taiwan's military held its own live-fire exercises in a show of readiness to thwart a potential attack.
The Chinese government objects to Taiwan having any official contact with foreign governments, particularly with a high-ranking congressional leader like Ms Pelosi.
A Taiwanese broadcaster showed video of a US government plane landing about 7pm on Sunday at Songshan Airport in Taipei, the Taiwanese capital. Four members of the delegation were on the plane.
Mr Markey met South Korean President Yoon Suk Yeol earlier on Sunday in South Korea before arriving in Taiwan on a separate flight at Taoyuan International Airport, which also serves Taipei.
WATCH: China and Taiwan: How their militaries compare.
Mr Markey, who chairs the Senate Foreign Relations East Asia, Pacific, and International Cybersecurity Subcommittee, and members of the delegation will reaffirm the United States' support for Taiwan.
Chinese warplanes have continued crossing the midpoint of the Taiwan Strait on a daily basis even after the conclusion of the military exercises last Wednesday, with at least 10 doing so on Sunday, Taiwan’s Defence Ministry said.
The 10 fighter jets were among 22 Chinese military aircraft and six naval ships detected in the area around Taiwan by 5pm. on Sunday, the ministry added.
A senior White House official on Asia policy said late last week that China had used Ms Pelosi's visit as a pretext to launch an intensified pressure campaign against Taiwan, jeopardising peace and stability across the Taiwan Strait and in the broader region.