
Taiwan is bracing for a potential show of force from China as US House Speaker Nancy Pelosi was expected to arrive on the island late Tuesday.
Her visit - which is not backed by the White House - would be the first by such a senior US official in decades.
Pelosi is the third-highest ranking official in the US government and a long-time critic of Beijing.
China has repeatedly warned against the visit and on Tuesday said the US would "pay the price".
Taiwan is a self-ruled island, but claimed by China, which sees it as a breakaway province.
Foreign ministry spokeswoman Hua Chunying said China had been in communication with the US about sensitivity of the visit.
"The US side will bear the responsibility and pay the price for undermining China's sovereign security interests," she said.