Xu Xijin has established himself over the years as a hardline defender of the Chinese Communist Party

The editor-in-chief for The Global Times, a state-funded newspaper in China, asked Monday if the United States is “mentally retarded” for rejecting Beijing’s broad territorial claims in the South China Sea, a region with long-standing disputes between China and other Southeast Asian countries.

In a retweet of an article about Washington’s statement, Global Times editor-in-chief Hu Xijin accused the U.S. of trying to provoke a conflict between China and surrounding nations.

“The US issued the statement four years after the South China sea ruling. Is Washington mentally retarded and slow in action?” Xijin wrote. “Who can’t see you want to instigate ASEAN-China clash and meak ASEAN the cannon fodder of US’ strategy against China? Do you think other people are fools?”

Xijin has earned a reputation over the years for his belligerent rhetoric and inveterate support of the Chinese Communist Party. He has been particularly outspoken in his opposition to pro-democracy protesters in Hong Kong, likening them to ISIS terrorists.

In an editorial published last November, he told Hong Kong police they have nothing to be scared of because they have the backing of “Chinese soldiers and People’s Liberation Army in Hong Kong” who can “provide support at any time.”

Xijin’s less than diplomatic rhetoric against Washington on Monday comes amid Beijing accusing the U.S. of trying to sow discord between China and the Southeast Asian countries with which it has long-standing territorial disputes in waters that are both a vital international shipping lane and home to valuable fisheries.

“The United States is not a country directly involved in the disputes. However, it has kept interfering in the issue,” the Chinese Embassy in Washington said on its website. “Under the pretext of preserving stability, it is flexing muscles, stirring up tension and inciting confrontation in the region.”

U.S. Secretary of State Mike Pompeo, in a statement released Monday, said the U.S. now regards virtually all Chinese maritime claims outside its internationally recognized waters to be illegitimate. The new position does not cover land features above sea level, which are considered to be “territorial” in nature.

Pompeo’s statement marks a major shift in America’s South China Sea policy. Previously, the U.S. had only insisted that maritime disputes between China and its smaller neighbors be resolved peacefully through U.N.-backed arbitration.

Both Indonesia and the Philippines joined Pompeo in calling on China to abide by an international arbitration court ruling in 2016 that disqualified many of China’s claims.

Chinese foreign ministry spokesperson Zhao Lijian reiterated China’s position that it has had effective jurisdiction over the islands, reefs, and waters of the South China Sea for more than 1,000 years.

China’s emergence as a military power and its ambitions to extend its offshore reach have come into conflict with the U.S., which has been the dominant naval power in the western Pacific in the post-World War II period.