US President Donald Trump said Friday that he and North Korean leader Kim Jong Un have "great chemistry" and claimed the stand-off with the nuclear-armed Asian nation is "largely solved."
Trump, speaking to reporters outside the White House, said he had given his "very direct" telephone number to Kim, adding: "He can now call me if he has any difficulty."
"That's a very important thing," Trump said. "We have communication."
In a video message released later by the White House, Trump said Tuesday's summit with the young North Korean leader in Singapore was "open, direct and very, very productive."
"If there's a chance at peace, if there's a chance to end the horrible threat of nuclear conflict then we must pursue it at all costs," he said.
The results of the Singapore meeting, at which Kim and Trump signed a pledge "to work towards complete denuclearization of the Korean Peninsula," have been greeted with skepticism by many observers.
Kim has not yet taken any concrete step to dismantle his nuclear programs.
Trump said Secretary of State Mike Pompeo would be "working directly with North Korea" in the coming weeks and months to "implement the denuclearization deal."
"In the meantime, sanctions will remain in place," he added.
Trump's unilateral decision to reduce tension by cancelling joint military exercises by US and South Korean forces meanwhile appeared to catch both close ally Seoul and some Pentagon officials by surprise.
But Trump recalled that when he came to office last year, his predecessor Barack Obama had warned that North Korea's growing missile and nuclear threat was the United States' "most dangerous problem."
"I have solved that problem," Trump told reporters. "Now we're getting it memorialized and all, but that problem is largely solved.
"We signed a very good document," he added. "But more importantly than the document, I have a good relationship with Kim Jong Un.
"We have a great chemistry together."
- 'Possible new avenue to peace' -
Defense Secretary Jim Mattis on Friday praised a "possible new avenue to peace" with North Korea, but warned the United States must remain vigilant to countries pursuing nuclear weapons.
But Trump seems keen to claim a quick diplomatic victory, and the halt to US military exercises on the peninsula is a significant concession to both Pyongyang and Washington's rival China.
Some of Trump's domestic critics condemned his decision to halt what the president calls "war games" with South Korea -- using a pejorative term for military drills that US officials have previously rejected.
"Making unnecessary and unreciprocated concessions is not in our interests -- and it is a bad negotiating tactic," Republican Senator John McCain said.
"Parroting Chinese and North Korean propaganda by saying joint exercises are 'provocative' undermines our security and alliances."
US and South Korean forces have trained together for decades, and routinely rehearse everything from beach landings in the North to pre-emptive "decapitation" strikes targeting the North Korean regime.
Pyongyang typically reacts furiously. Following drills last year, the North fired ballistic missiles over Japan, triggering global alarm and ratcheting up a diplomatic war of words between Trump and Kim.
Those harsh exchanges are now apparently over -- since the summit, Trump has lavished praise on Kim, once a global pariah credibly accused of torturing and starving tens of thousands of his own citizens.
- Sarcastic remark -
Trump praised Kim again on Friday, in what turned into a lengthy unplanned interview with his favorite television show "Fox and Friends."
"Hey, he is the head of a country and I mean he is the strong head. Don't let anyone think anything different. He speaks and his people sit up at attention. I want my people to do the same," he said.
Trump later told reporters that his remark about Americans standing to attention was "sarcasm."
But, asked why he had praised Kim at all, given his history of rights abuses and the death of US student Otto Warmbier after he fell into a coma in North Korean custody, Trump set up a stark choice.
"Because I don't want to see a nuclear weapon destroy your family," he told one reporter.
And as to the military drills, Trump said he had wanted to halt them long before he travelled to Singapore to meet Kim.