China views democratically governed Taiwan as its own territory, despite the strong objections of the island's government.
"This is a serious warning against Taiwan independence separatist forces colluding with external forces to provoke," it said.
China has a particular dislike of Lai for his previous comments that he was a "practical worker for Taiwan independence".
The United States, like most countries, has no formal ties with Taiwan but is its strongest international backer, bound by law to provide the island with the means to defend itself.
China has over the past three years ramped up military pressure on Taiwan, including sending military aircraft and warships near the island.
Persons:
William Lai, Nancy Pelosi, Tsai Ing, Kevin McCarthy, Lai, Deb Haaland, King Felipe VI, Luiz Inacio Lula da Silva, Casey Hall, Ben Blanchard, Greg Torode, William Mallard
Organizations:
Joint Staff Office, Defense Ministry of Japan, Reuters, Eastern Theatre Command, U.S . House, U.S, Beijing, Communist Party, Thomson
Locations:
Okinawa, Miyako, SHANGHAI, TAIPEI, Taiwan, United States, Taipei . Lai, Paraguay, China, Taipei, California, South, Asuncion