US president boasts North Korea stand-off 'largely solved'

President Donald Trump declared Washingtons nuclear stand-off with North Korea "largely solved" on Friday, after he gave young autocrat Kim Jong Un his telephone number and cancelled US war games.

Hailing the success of this week's summit in Singapore, Trump told reporters in Washington that he is now in direct contact with Kim and that their "good relationship" had ended the risk of conflict.

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.

And Trump's unilateral decision to reduce tension by cancelling "provocative" joint exercises by US and South Korean forces 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 after a spontaneous visit to a television crew working on the White House lawn.

"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.

"That's a very important thing. I can now call him. I gave him a very direct number. He can now call me if he has any difficulty. We have communication."

Kim has not yet taken any concrete step to dismantle his nuclear programs, and US Secretary of State Mike Pompeo has warned sanctions must remain in place until "full denuclearization" is achieved.

Long and slow

But Trump seems keen to claim a quick diplomatic victory and the halt to major US military exercises on the peninsula is a significant concession to both Pyongyang and Washington's rival China.

Many experts in Washington agree with the conclusion of a leaked Israeli government analysis that there were "substantive gaps" between US goals going into the summit and the vague language of the statement.

"Despite Trump's declarations about quick changes expected in North Korea's policy, the way to substantive change -- if that ever comes -- is still long and slow," the report warned.

Some of Trump's domestic critics have also 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, and 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, and insisted that "war games" is his own preferred term.

"I hated it from the day I came in. Why aren't we being reimbursed?" he demanded, returning to his long-standing claim that US allies like South Korea should repay the costs of their defense.

"I saved us a lot of money."