Washington: The US has never been so close to getting rid of North Korean nuclear weapons, President Donald Trump has said, exuding confidence that his planned summit with the North's leader, Kim Jong Un, will go ahead.

"The United States has never been closer to potentially having something happen with respect to the Korean peninsula that can get rid of the nuclear weapons, can create so many good things, so many positive things, and peace and safety for the world," Trump told reporters during a Rose Garden joint news conference with the visiting Nigerian President Muhammadu Buhari.

"So, we'll see what happens. You know, I often say, Who knows? Who knows? Maybe a lot of things change," he said responding to a question on the latest developments in the Korean Peninsula.

Trump has accepted an invitation for a meeting with Kim. The meeting is scheduled to take place soon, possibly in the Demilitarised Zone (DMZ) straddling the border between the two Koreas.

"There's something that I like about it, because you're actually there - if things work out, there's a great celebration to be had on the site, not in a third party country. So we are looking at the possibility of doing it in that location. We're also looking at various other countries, including Singapore," he said.

"I will say this: The good news - everybody wants us. It has the chance to be a big event," he said as he praised Kim for his recent statements.

"Kim Jong Un, who has been very open and very straightforward so far - I can only say, again, so far. But he's talking about getting rid of the site, which was their big site. He's talking about no research, no launching of ballistic missiles, no nuclear testing. And he has lived up to that for a long period of time, a longer period of time than anybody has seen," Trump said.

The US is looking at that as a potential site.

"I think it would be very interesting. I think it would be a great celebration if it works out well. If it doesn't work out well, that's the way it goes," the US President said.

Trump expressed confidence that the summit would happen.

"I think the summit is going to happen. They very much want it. We certainly would like to see it. I think the summit will happen. And personally, I think it's going to be a success, but we'll see," he said.

"If it's not a success, I will respectfully leave. It's very simple," Trump said, seeking to strike a balance between optimism and skepticism about his upcoming summit with Kim.

Nigerian President Buhari congratulated the leaders of the North and South Korea on their historic summit, and applauded them for the positive commitment they have made towards denuclearization of the Korean peninsula. Trump also came in for praise from Buhari.

"President Trump deserves a great deal of credit for his statemanly role in transforming so dramatically the course of events in that region," he said.