On Tuesday, Trump upended much of that work in 140 characters, tweeting that Chinese efforts have "not worked out."
"While I greatly appreciate the efforts of President Xi & China to help with North Korea, it has not worked out. At least I know China tried," Trump wrote.
The tweet, which came hours before the United States and China were set to meet in Washington to talk about North Korea, caught multiple Trump administration officials off guard, leaving them scrambling as they tried to figure out what exactly the President meant.
One Trump administration official said bluntly they didn't know what Trump was referencing when asked what the tweet meant.
Another cautioned against reading too much into the message, arguing that there was no meeting earlier in the day that could have spurred the comment or that the tweet foretold some sort of unilateral action against North Korea.
Hanging over the tweet -- and Wednesday's meeting -- is the death of Otto Warmbier
, an American college student who died earlier this week after spending 17 months in detention in North Korea. His family believes he was tortured into a vegetative state. Trump condemned the "brutal regime" and lamented the loss of a young man "in the prime of life."
Trump had made clear in the past that his preference was to work with China on North Korea, but that he was willing to go after them alone.
"I have great confidence that China will properly deal with North Korea. If they are unable to do so, the U.S., with its allies, will! U.S.A.," he tweeted in April.
Trump's blunt tweet thrusts the typically off-the-cuff President -- who cast himself as America's greatest deal-maker during the 2016 campaign -- into the perilously sensitive arena of international diplomacy.
His comment could signal he is ready to play hardball with the Chinese, or at least send a message to China that the United States feels they are not coming to the table with a strong hand because of their continued trade with North Korea. Senior diplomatic officials said the plan is to use trade as a weapon against China.
But the comment could just as easily weaken Trump's hand with the Chinese, laying the American position bare and making it clear that the United States is prepared to deal with North Korea alone.
Secretary of State Rex Tillerson and Secretary of Defense Jim Mattis will head up negotiations with China's top diplomat, State Councilor Yang Jiechi.
Chinese President Xi Jinping met with Trump at the President's private Florida estate in April, a meeting that both leaders said warmed relations between the countries. (Trump later vividly recounted their interaction, including a detailed description of the "beautiful" chocolate cake
They spoke over the phone that month as well.
Following the meeting, China's role was one of the administration's main talking points in explaining North Korea.
"I think the President's direct engagement with President Xi of China and the fact that now you've seen China turning back coal shipments from North Korea, making changes in the ability of people to travel by air from Pyongyang into China and other measures that they may well take in the future demonstrates the hands-on diplomacy that President Trump has brought to this," Pence told CNN. "That's what it will take."
Trump also defended his decision not to label China a currency manipulator -- something he pledged during the campaign -- because of their work on North Korea.
"Why would I call China a currency manipulator when they are working with us on the North Korean problem," Trump wrote in April. "We will see what happens!"