Summit with Kim takes world 'a big step back from potential nuclear catastrophe': Trump

US President Donald Trump on Wednesday said his unprecedented summit with Kim Jong-un has averted a "nuclear catastrophe" and thanked the North Korean leader for taking the "first bold step" towards a bright new future for his people. 

Kim on Tuesday pledged to work towards the "complete denuclearisation" in return for security guarantees from the US as he and Trump wrapped up a historic summit in Singapore. 

"I want to thank Chairman Kim for taking the first bold step toward a bright new future for his people. Our unprecedented meeting, the first between an American President and a leader of North Korea proves that real change is possible!" Trump said in a series of tweets aboard Air Force One on his way back to Washington DC.

"The World has taken a big step back from potential Nuclear catastrophe!" he said. 

"No more rocket launches, nuclear testing or research! The hostages are back home with their families. Thank you to Chairman Kim, our day together was historic!"

North Korea had declared earlier this year that since it had achieved all it wanted with regard to its nuclear programme, it would suspend its tests. 

Since then, Pyongyang has closed down two test sites. Trump announced yesterday that Kim had informed him that he would be shutting down a third, one that tested missile engines.

The US President said there was "no limit to what NoKo (North Korea) can achieve when it gives up its nuclear weapons and embraces commerce & engagement with the world. 

"Chairman Kim has before him the opportunity to be remembered as the leader who ushered in a glorious new era of security & prosperity for his citizens!" Trump said in another tweet.

Trump described his Singapore trip as a "truly amazing" visit.

"Great progress was made on the denuclearisation of North Korea. Hostages are back home, will be getting the remains of our great heroes back to their families, no missiles shot, no research happening, sites closing...," he said.

"Got along great with Kim Jong-un who wants to see wonderful things for his country. As I said earlier today: Anyone can make war, but only the most courageous can make peace!" Trump said in another tweet.

Meanwhile, US Secretary of State Mike Pompeo headed for Seoul and then to Beijing to brief S Korean and Chinese counterparts on the summit meeting between Trump and Kim. Soon after the Singapore summit concluded, Pompeo called his counterparts in South Korea and Japan to brief them of the talks.