SINGAPORE — Defense Secretary Jim Mattis tried to lower the temperature on the array of hostilities between Washington and Beijing on Thursday, saying it is up to the militaries of the two competing global superpowers to act as a stabilizing force amid rising political tensions.
During an hour-and-a-half meeting with his Chinese counterpart, Mr. Mattis sanded down some of the sharp edges from Vice President Mike Pence’s pointed critique of China this month. Mr. Mattis urged the two militaries to talk through their many differences and even repeated an invitation for Wei Fenghe, China’s defense minister, to visit the United States, according to a senior Defense Department official who was in the meeting.
But the cordial tone belied deep tensions that showed no signs of abating on Thursday. China, as it usually does, brushed off Mr. Mattis’s complaints about Beijing’s continued militarization of disputed islands in the South China Sea.
Meanwhile, other countries present at a meeting in Singapore of Southeast Asian nations continued to resist American entreaties to add their voices to the American challenge of China’s claims in the disputed area. And two of those countries — Malaysia and Thailand — even prepared for a joint naval exercise with China that American officials worry is part of a larger effort by Beijing to peel away American allies.
Mr. Mattis, for his part, was hampered by the continued fallout and speculation from President Trump having questioned on Sunday whether the defense chief would remain on the job, calling Mr. Mattis “sort of a Democrat, if you want to know the truth,” during in interview with CBS’s “60 Minutes. ” Mr. Mattis later told reporters that Mr. Trump had called him to reassure him that he was “100 percent” behind the defense secretary, but in Asia there has been speculation about how long Mr. Mattis will be around.
The Mattis-Wei meeting comes as the United States and China continue to lurch from one crisis to the next. President Trump accused China last month of meddling in the American midterm elections, an accusation Beijing rejected.
Mr. Pence’s Oct. 4 speech has been widely viewed as foreshadowing a new Cold War between the United States and China, and with the exception of Mr. Mattis, the Trump administration has only turned up the volume since.
On Wednesday the White House said it planned to withdraw from a 144-year old postal treaty that has allowed Chinese companies to ship small packages to the United States at a discounted rate, part of a concerted push by Mr. Trump to counter China’s dominance and punish it for what the administration says is a pattern of unfair trade practices.
The military relationship that Mr. Mattis is pushing as an island of stability is also taking hits. Mr. Mattis was supposed to begin his trip to Asia this week with a stop in Beijing for talks with Mr. Wei, but China canceled the visit, citing annoyance over sanctions Mr. Trump imposed on a Chinese state military company for buying weapons from Russia, and Washington’s plans to sell $330 million in military equipment to Taiwan, the self-governing island that Beijing claims as its own.
The biggest source of tension between the Pentagon and Beijing continues to be the South China Sea. China claims almost all the South China Sea, and strongly protests American military patrols there. The United States, for its part, considers the sea to be international waters and sends bombers and warships through every so often to make that point.
During his talk with Mr. Wei, Mr. Mattis introduced a new dynamic into the standard talking points over the South China Sea issue, according to Randall G. Schriver, the Pentagon’s top official for Asia and the Pacific, who was in the meeting. Mr. Mattis sought to convey what he said were concerns of other Asia-Pacific countries over Chinese claims on the South China Sea.
“He talked about the reactions that he hears from other countries and their concern and confusion over China’s actions not necessarily matching their words,” Mr. Schriver said.
American officials have recently started complaining privately that the United States does the bulk of the naval work when it comes to overtly challenging China in the South China Sea, with numerous so-called Freedom of Navigation trips, during which American warships sail within 12 miles of the disputed islands.
China always objects to the trips — last month a Chinese warship came within 45 yards of an American naval destroyer Decatur, as it conducted a Freedom of Navigation operation in the South China Sea. The Pentagon characterized the maneuver as unsafe and unprofessional.
“When the Chinese ships are putting bumpers over the side,” Mr. Mattis told reporters on the plane at the beginning of his Asia trip, “You don’t do that when you’re out in the middle of the ocean, unless you’re intending to run into something.”
He vowed that American ships would continue to traverse what the United States views as international waters.
But it is one thing for an American warship to challenge a Chinese one; it is a far bigger challenge for a smaller navy to do so. Britain conducted a freedom of navigation operation in August — China complained about that too — but China’s smaller Asian neighbors have been loathe to follow suit.
During the meeting, Mr. Mattis brought up the other countries.
“I think his point was that in some instances, other countries may not have the confidence, given China’s strength, to always speak up,” Mr. Schriver told reporters after the meeting. “But he wanted to let minister Wei know that he hears about it a great deal from other countries.”
Mr. Schriver acknowledged though, that for individual countries, “it’s sovereign decisions on how they approach China bilaterally.”