President Donald Trump, in unprecedented fashion, has been able to get the Chinese government to turn the screws on North Korea in hopes of getting Kim Jong Un to halt military provocations, according to a former diplomat who has advised Republican and Democratic presidents.

“The Chinese have done more under President Trump’s prodding than any other American president. They signed on to the UN sanctions. There are now individual Chinese sanctions; the central bank governors instructed banks in China to wind up loans to North Korea,” Nicholas Burns told CNBC on Friday. He appeared on “Squawk Box,” a week before Trump embarks on a trip to Asia, which includes stops in China and South Korea.

“The Chinese are clearly frustrated with the North Koreans. The Chinese don’t want a war on the Korean Peninsula. They want trade,” said Burns, who served as U.S. ambassador to NATO and was the State Department’s third-ranking official during George W. Bush‘s presidency. He also advised the administrations of George H.W. Bush and Bill Clinton.

Chinese President Xi Jinping, who was just given a major governing mandate, will be “eager to cooperate” with Trump, said Burns, a professor at the Harvard Kennedy School of Government. “The president [Trump] has obviously gone slow on any kind of major [trade] sanctions against China because he’s prioritizing the North Korean issue. The Chinese understand that.”

When he was on CNBC earlier this month, Burns predicted Xi would become “the most powerful Chinese leader in 45 years.” This week, it happened when Xi’s political thought was enshrined in the ruling Communist Party’s constitution, putting him in the same company as the founder of modern China, Mao Zedong.

Burns said the best scenario for Trump on his trip would be to persuade North Korea’s Kim through a unified international alliance to agree to negotiations.

“Here’s where President Trump has not done well,” Burns said. “What we’re trying to do is practice strategic deterrence. We’re trying to convince Kim Jong Un that if he attacks us there’s going to be an unacceptably strong response from the United States back.”

Secretary of State Rex Tillerson and Defense Secretary James Mattis have been together in delivering that message, Burns said. “They’ve been very clear. The president has not. The president has muddied the waters.”

“The president has been intimating in his tweets that maybe the United States will act unilaterally. That’s not smart,” Burns continued. “You don’t want to raise the risk of a mistake here by Kim Jong Un.”

Mattis visited the Demilitarized Zone between South and North Korea on Friday, calling for a “diplomatic solution” to get Kim to stop nuclear weapons tests and missile test launches.

It’s unknown whether Trump will visit the DMZ. Burns sees it as a long shot.

“I think it may too provocative. Given the fact that the president is not disciplined and his advisors never know what he’s going to say or not say,” Burns said.