US President Donald Trump on Wednesday expressed caution about his June 12 meeting with North Korean leader Kim Jong Un after Pyongyang threw the summit in Singapore into doubt.

North Korea has said it may skip the meeting if the United States continues to demand that it unilaterally abandon its nuclear weapons.

We'll have to see," Trump told reporters in the Oval Office when asked if the summit was still on.

"No decision, we haven't been notified at all ... We haven't seen anything, we haven't heard anything," he added.

Trump insisted he would continue to demand denuclearization despite North Korea's threat.

Read more: Korea summit 'is a great opportunity'

Cancellation of the much-anticipated summit with Kim Jong Un — the first meeting between a serving US president and a North Korean leader — would be a setback for what is being touted as President Trump's biggest diplomatic achievement.

'Still hopeful'

Earlier, the White House said it was "still hopeful" the summit would take place.

"The president is ready if the meeting takes place," White House spokeswoman Sarah Huckabee Sanders told US broadcaster Fox News. "If it doesn't, we'll continue the maximum pressure campaign that's been ongoing."

Huckabee Sanders said the North Korean comments were "not something that is out of the ordinary in these types of operations."

A senior US official told Associated Press news agency that there was a direction from the Oval Office to White House aides and other US national security agencies to downplay the North Korean threats and not "take the bait" by overreacting to the provocation.

'Libyan model'

North Korea's vice foreign minister, Kim Kye Gwan, said on Wednesday that Pyongyang wouldl reconsider attending the summit with the US.

"We are no longer interested in a negotiation that will be all about driving us into a corner and making a one-sided demand for us to give up our nukes," Kim said.

Kim's warning came after North Korea abruptly canceled a high-level meeting with South Korea to protest US-South Korean military exercises.

Kim especially criticized recent comments from Trump's top security adviser, John Bolton, about how North Korea should follow the "Libyan model" of nuclear disarmament and provide "a complete, verifiable and irreversible dismantlement."

In an interview with Fox News Radio, Bolton said the remarks against him were "nothing new." He said the US would not soften its demands.

"I think that's where the president is; we are going to do everything we can to come to a successful meeting, but we are not going to back away from the objective of that meeting which is complete, verifiable and irreversible denuclearization of North Korea."

ap/rc (AFP, Reuters, AP)