US President Donald Trump on Friday pulled the plug on a weekend trip to North Korea by his top diplomat, while taking a swipe at China over efforts to disarm the nuclear state.

“I have asked Secretary of State Mike Pompeo not to go to North Korea, at this time, because I feel we are not making sufficient progress with respect to the denuclearization of the Korean Peninsula,” Trump said by tweet.

“Additionally, because of our much tougher Trading stance with China, I do not believe they are helping with the process of denuclearization as they once were (despite the UN Sanctions which are in place),” Trump said.

In another tweet, the president added Pompeo would still head to North Korea “in the near future,” saying this would likely occur when the US-China trading relationship is “resolved.”

“In the meantime I would like to send my warmest regards and respect to Chairman Kim. I look forward to seeing him soon!” Trump said.

Pompeo on Thursday had said he would return to North Korea next week for the next stage in ensuring the “final, fully verified denuclearization of North Korea.”

The trip would have been Pompeo’s fourth to North Korea, and the second since a historic summit on June 12 between Trump and the country’s strongman leader Kim Jong Un.

Trump, who relishes unpredictability in negotiating, had at one point canceled that summit, citing North Korea’s “open hostility.”

But he soon backtracked and the summit went ahead.