Beijing appears to be sending fresh signals about its view on North Korea, in order to convince U.S. President Donald Trump to take less aggressive action against the rogue nuclear state, several political analysts say. "One thing we're seeing is a tactical adjustment on Beijing's part to Trump," said John Delury, associate professor of Chinese studies at Yonsei University in Seoul, South Korea. "There's a kind of game here where Beijing is playing along to a certain extent, almost to call Trump's bluff, and to get the Americans to recognize they have the key in their hand to unlock the problem." "The key is not military. When you start to look carefully at the military options, they are horrific, just given the economic vulnerabilities of everyone in this neighborhood," he said. "The key the U.S. has is diplomacy." At least two-thirds of North Korea's trade is with China, giving Beijing tremendous leverage over the state. Recent reports indicate that Chinese authorities are beginning to test that power.

After a North Korean missile test in February, Chinese authorities suspended coal imports from the state for the rest of the year. Media reports citing Chinese academics and opinion pieces in the Beijing-backed Global Times have raised the prospect of cutting oil exports to North Korea. Such action would severely hurt the small, North Korean economy and indicate China's seriousness on curbing the pariah state, analysts said.

The chimneys of a power station amid the Pyongyang city skyline. Ed Jones | AFP | Getty Images

"Clearly the Chinese regime is losing patience with North Korea," said Michael Hirson, Asia director at consulting firm Eurasia Group. "We're seeing some incremental steps that the Chinese may be in favor of doing more." "I think China is signaling to both sides, to the U.S. that China is doing more, that China is acting in good faith to head off a crisis in North Korea," Hirson said. "Primarily they're telling the U.S. that ultimately China feels the only solution in North Korea is one that involves diplomacy and getting North Korea to the table." As a candidate, Trump said he would be prepared to meet with North Korean leader Kim Jong Un and talk things out "over a hamburger."

But Trump has changed his tone since winning the election, and the chance of negotiations appears slimmer. Trump has repeatedly pressured China to act on trade, and offered better deals with the U.S. in return. Vice President Mike Pence said during a visit to South Korea this month that "the era of strategic patience is over" with North Korea. The U.S. ordered the USS Carl Vinson aircraft carrier strike group to sail toward the Korean peninsula — after some confusion within the administration about when, exactly, that was happening. Pyongyang responded by saying it was ready to sink the carrier. Meanwhile, two Japanese destroyers have joined the U.S. carrier group. And there's even a chance the United States could build some level of influence over North Korea itself. "The main leverage we have is the North Koreans want a new relationship with us because they don't want to become too dependent on China," said Leon Sigal, director of the Northeast Asia Cooperative Security Project. "They don't trust the Chinese."

Chinese sanctions alone may not cut it