The Chinese foreign ministry on Wednesday criticized U.S. Secretary of State Mike Pompeo for congratulating the president of Taiwan on winning a second term. By doing so, China claims that Pompeo did major damage to the two superpowers’ political relationship.

Tsai Ing-wen was recently re-elected as president of Taiwan. Under its “One China” policy, the Chinese government has insisted that Taiwan is a part of China and not its own nation, a stance that Tsai has refused to accept.

Aside from the sale of arms, the U.S. has no official relationship with Taiwan. Pompeo was the highest-ranking U.S. official to issue a statement on Tsai’s reelection and the only Secretary of State in history to congratulate a Taiwanese president for their election. Merely acknowledging Tsai as a “president” has also caused offense to the Chinese government.

“I would like to congratulate Dr. Tsai Ing-wen on the commencement of her second term as Taiwan’s President,” Pompeo said in his statement. “Her re-election by a huge margin shows that she has earned the respect, admiration, and trust of the people on Taiwan. Her courage and vision in leading Taiwan’s vibrant democracy is an inspiration to the region and the world.”

“China urges the US side to immediately correct its mistakes,” the Chinese foreign ministry said in response. “The Chinese side will take necessary countermeasures to respond to the above-mentioned erroneous actions by the US side. And the US side should bear the consequences arising therefrom.”

While Pompeo’s full intentions with the message are currently unclear, it comes during a time of increasing tension between the U.S. and China. In addition to longstanding trade disputes and accusations of China stealing intellectual property, the U.S. has also called into question China’s initial handling of the COVID-19 outbreak in December 2019.