UNITED NATIONS (AP) — U.S. Secretary of State Mike Pompeo said Thursday he is sending U.N. Ambassador Kelly Craft to Taiwan next week to show “what a free China could achieve,” an announcement that sparked sharp criticism from Beijing and a warning that “the United States will pay a heavy price for its wrong action.”

Pompeo called Taiwan “a reliable partner and vibrant democracy that has flourished despite CCP (Chinese Communist Party) efforts to undermine its great success.”

China’s U.N. Mission said in a statement from its spokesperson that Beijing “firmly opposes” Craft’s visit. It said that “there is only one China in the world and the Taiwan region is an inalienable part of China’s territory.”

“The United States will not succeed in its attempt to harm China’s core interests through political manipulation on the Taiwan question,” the unidentified spokesperson said. “We wish to remind the United States that whoever plays with fire will burn himself.”

American relations with democratic Taiwan have warmed, largely due to strong bipartisan support in the U.S. Congress, but the Trump administration has also been willing to defy Beijing’s threats and promote an alternative to Chinese Communist Party authoritarianism.

The U.S. outreach to Taiwan has exacerbated tensions between Washington and Beijing over the COVID-19 pandemic, trade, Hong Kong and the South China Sea.

China has been stepping up its threats to bring the self-governing island under its control by military force with frequent war games and aerial patrols. It has been using its diplomatic clout to stop Taiwan from joining any organizations that require statehood for membership.

Taiwan left the United Nations in 1971 when China joined and is excluded from all of its agencies, including the World Health Organization’s assembly, where Taiwan’s observer status has been stripped. At the same time, it has one of the most robust public health systems in the world and has won praise for its handling of the coronavirus outbreak.

The Trump administration has been pressing for Taiwan’s inclusion as a separate entity in international organizations like the WHO and the International Civil Aviation Organization.

The U.S. Mission to the United Nations said Thursday night that Craft will travel to Taiwan on Jan. 13-15 -- less than a week before the inauguration of Joe Biden and the end of Donald Trump’s presidency -- to “reinforce the U.S. government’s strong and ongoing support for Taiwan’s international space.”

Kraft will meet with senior Taiwan counterparts, members of the diplomatic community, and speak at the Institute of Diplomacy and International Affairs on Jan. 14 “on Taiwan’s impressive contributions to the global community and the importance of Taiwan’s meaningful and expanded participation in international organizations,” a mission announcement said.

Craft had lunch in September with Taiwan’s top official in New York, James K.J. Lee, director of the Taipei Economic and Cultural Office in New York, a meeting she called “historic.” The meeting came just before U.S. Undersecretary of State Keith Krach visited Taiwan in the highest-level visit by a State Department official to the island in decades and met Taiwanese President Tsai Ing-wen and other senior officials.

Krach’s visit followed a high-profile trip in August by U.S. Health Secretary Alex Azar, the highest-level U.S. Cabinet official to visit since the U.S. switched formal relations from Taiwan to China in 1979.

The U.S. has maintained unofficial ties with Taiwan since the official diplomatic break and is the island’s most important ally and provider of defense equipment.