Speaker of the US House of Representatives Nancy Pelosi, a staunch critic of Beijing’s policies, arrived in Taiwan on Tuesday for a visit that China warned would undermine relations between the two countries, Reuters writes.

• The explosive potential of Nancy Pelosi’s visit to Taiwan, an island that has brought the US and China to the brink of war several times in recent decades

Pelosi has been on a tour of Asia that includes visits to Singapore, Malaysia, South Korea and Japan.

Beijing warned on Tuesday that the United States would bear “responsibility” for Nancy Pelosi’s visit to Taiwan and would have to “pay the price.”

“The United States will definitely bear responsibility (for the consequences) and will have to pay the price for the attack on China’s sovereignty and security,” Chinese diplomatic spokeswoman Hua Chunying said.

On Tuesday, China sent warplanes to the Middle Line, the unofficial demarcation line in the Taiwan Strait between mainland China and Taiwan.

Its forces have also conducted exercises, and China’s military’s Eastern Command released a video saying it was “fully prepared for any eventuality.”

China considers the island of Taiwan part of its territory and has repeatedly warned the US about the risk that a visit by a high-ranking American official to Taipei could become a serious problem for Beijing.