The summit with the Democratic People's Republic of Korea remains on track, US President Donald Trump said on Thursday, promising the DPRK would get "protections" if a deal were made, but threatening it would face grave consequences if things went otherwise.

Despite the DPRK's threat on Wednesday to cancel the summit between him and DPRK leader Kim Jong-un next month, Trump said on Thursday that preparations were underway.

"Right now, we're dealing with them. We're dealing — as I said just a little while ago — we're dealing as though nothing happened," he said at the White House.

White House spokeswoman Sarah Sanders said, "If the North Koreans want to meet, we'll be there."

Trump said he is "willing to do a lot" to provide security guarantees to Kim. "The best thing he could do is make a deal," he said.

The president said if Kim were to agree to denuclearize, "he'll get protections that would be very strong," the Associated Press reported on Thursday.

"He would be there, he would be running his country, his country would be very rich," Trump said.

Trump also seemed to distance himself from the "Libya model" of denuclearization for the DPRK, a notion expressed earlier by Trump's National Security Advisor John Bolton that had irked the DPRK.

"The Libyan model isn't a model that we have (in mind) at all when we're thinking of North Korea," Trump said.

But he said, "that model would take place if we don't make a deal, most likely," according to an Agence France-Presse report that said Trump made the remarks while sitting at arm's length from Bolton in the Oval Office.

Chinese Foreign Ministry spokesman Lu Kang, when asked by reporters if China endorses the "Libya model" proposed by Bolton, said, "I am certain that you have never heard us saying that we endorse the Libya model."

"China always maintains that all relevant parties should engage in dialogues to advance the political settlement of the peninsula issue and address their concerns in a balanced way, including the legitimate security concerns of the DPRK," Lu told a regular news briefing on Thursday.

Measures adopted by Pyongyang recently deserve endorsement, and the parties concerned, particularly Washington, should cherish the rising opportunities for peace, State Councilor and Foreign Minister Wang Yi told reporters in Paris.

Wang said that relief from the tense situation was "hard won", and called on all parties concerned to work as promoters of peace, not the contrary.

He warned that China does not expect the reoccurrence of a scenario in which one side shows flexibility while the other side displays greater toughness, noting that there have been lessons in the past.

Abraham Denmark, director of the Asia Program at the Woodrow Wilson International Center for Scholars in Washington, said there was "a major error" in the US negotiation strategy.

"Kim won't back down from a threat, especially if he judges it lacks credibility," he said in a tweet on Thursday, adding that there must be "a third option between a deal and war".

The DPRK's first vice-foreign minister, Kim Kye-gwan, said on Wednesday that the country has no interest in a summit with the US if it's going to be a "one-sided" affair in which the DPRK is pressured to give up its nuclear weapons.

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