U.S. Says Most of China’s Claims in South China Sea Are Illegal

“The State Department, I think, was just looking for ways that we can more forcefully act and speak out in support of the smaller claimants who are getting bullied by China,” said Bonnie S. Glaser, a senior director for Asia at the Center for Strategic and International Studies. “And I think that comes across loud and clear in the statements. It’s all about supporting the actions of countries to fish and explore energy in maritime spaces that China has claimed.”

Daniel Russel, the assistant secretary of state for East Asia and the Pacific in the second Obama term, said that the Obama administration had accepted the tribunal’s 2016 ruling as “final and binding,” and that Mr. Pompeo’s statement was more “chest-pounding and angry invective about China” than a change in policy.

The Trump administration has been selective in its endorsement of international rulings from The Hague. It warned last month that international investigators looking into charges of war crimes by Americans in Afghanistan would face economic penalties and travel restrictions.

Global Times, a nationalist Chinese newspaper, published an opinion essay on Monday saying that the U.S. “desires to stir up troubles” over the South China Sea and that “it takes advantage of regional countries’ claims to sow discord between these countries and China. It portrays a bully image of China.” While the essay was published before the State Department announcement, it seemed to anticipate U.S. action, saying that Washington “certainly wouldn’t miss something like the anniversary of 2016 arbitration.”

Maritime claims are just one of several areas where the Trump administration has been applying greater pressure on China in recent months.

Robert C. O’Brien, the national security adviser, will address others this week during a visit to Paris, including the security of new 5G networks that incorporate Chinese-made hardware. A White House official said he would meet with his counterparts from France, Britain, Germany and Italy.

Last month, Mr. O’Brien gave a speech in Arizona saying that China’s president, Xi Jinping, saw himself as a “successor” to the Soviet dictator Joseph Stalin and warned that China sought to take advantage of the coronavirus crisis “to displace the United States as the leading global power.”

Edward Wong reported from Washington, and Michael Crowley from Amherst, Mass.