"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.

Pompeo was due to return to North Korea next week for what he described as the next stage in ensuring the "final, fully verified denuclearization of North Korea."

But Trump -- facing a slew of domestic problems and independent reports that North Korea has done little or nothing to roll back its nuclear program -- vetoed the plan.

Trump also stepped up his rhetoric against China, which has grown harsher as November congressional elections approach, with the two economic powers now embroiled in an escalating trade war.

"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.

- 'Largely solved' -

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.

Trump had previously claimed that he had "largely solved" the North Korea nuclear problem.

"I have solved that problem. That problem is largely solved," he said.

Despite that bold claim, the UN's International Atomic Energy Agency recently reported it had not seen any indication that nuclear activities in North Korea have stopped.

"The continuation and further development of the DPRK's nuclear programme and related statements by the DPRK are a cause for grave concern," said a report by the International Atomic Energy Agency (IAEA), referring to North Korea's official name.

North Korea is believed to be close to developing a miniaturized nuclear device and the ballistic missile capabilities to carry it anywhere in the continental United States.

Secretary of State Pompeo this week named a Ford Motor Co. executive as special envoy for North Korea to try and get disarmament back on track.

Stephen Biegun, 55, who is retiring as Ford's vice president for international governmental affairs, had been considered for the post of Trump's national security advisor before it went to John Bolton.

"Steve will direct the US policy towards North Korea and lead our efforts to achieve President Trump's goal of the final, fully verified denuclearization of North Korea, as agreed to by chairman Kim Jong Un," Pompeo said.