China’s increasingly aggressive activities around Taiwan — and its refusal to speak to the U.S. military through channels designed to avoid conflict — is fueling fears that the United States could be drawn into a third major war in the world.

Reestablishing those communication channels will be high on the agenda when President Biden talks with Chinese leader Xi Jinping this week, their first meeting in a year. But China is being deliberately unpredictable and incommunicative, analysts say, to keep the U.S. military off guard in the Pacific and to warn against American attempts to help defend Taiwan.

“It’s reached a very, very high level of tension” said Lyle Goldstein, director of Asia engagement at Defense Priorities, a think tank. Without a breakthrough that eases mistrust, the current “fairly acute crisis” will continue. “War could essentially happen any time,” he said.

Xi and Biden are due to meet on the sidelines of the Asia-Pacific Economic Cooperation summit in San Francisco, part of a broader effort to reset relations that have rapidly deteriorated amid heated technology competition, a rogue balloon and increasingly brazen Chinese military activity in the South China Sea and around Taiwan.

At the same time, as it tries to intimidate Taiwan, the Chinese military has conducted more than 180 risky intercepts against U.S. surveillance aircraft in the Pacific in the past two years, more than in the previous decade. The chairman of the Joint Chiefs of Staff, Gen. Charles Q. Brown Jr., said Friday that he had written to his Chinese counterpart urging the resumption of military communication channels that Beijing severed in retaliation for then-House Speaker Nancy Pelosi’s visit to Taipei last year.

It is “hugely important” to “ensure there is no miscalculation” between the militaries, he said.

White House national security adviser Jake Sullivan reiterated this Sunday. “The president is determined to see the reestablishment of military-to-military ties because he believes it’s in the U.S. national security interest,” he said on CBS’s “Face the Nation.”