Trump said a recent letter from North Korean leader Kim Jong Un confirmed the positive track, which he said has seen the hardline communist country promise to halt its nuclear missile test program and mount a combined bid with South Korea for the 2032 Olympic Games.

"We're making tremendous progress with respect to North Korea. Prior to becoming president, it looked like we were going to war with North Korea and now we have a lot of progress," Trump told journalists at the White House.

"A lot of tremendous things but very importantly no missile testing, no nuclear testing."

"The relationships, I have to tell you, at least on a personal basis, are very good. It is very much calmed down," Trump said.

An unprecedented June summit in Singapore between Trump and Kim aimed to break a decades-long standoff between the two countries, which have never formally ended the 1950-1953 Korean War.

However, critics accused Trump of naively playing into the North Korean's hands by giving him credibility with little concrete in return.