'Long way' to go on N Korea crisis: Trump

US President Donald Trump said the North Korean nuclear crisis is a long way from being resolved on Sunday, striking a cautious note a day after the North's pledge to end its nuclear tests raised hopes before planned summits with South Korea and the United States.

"We are a long way from conclusion on North Korea, maybe things will work out, and maybe they won't - only time will tell," Trump said on Twitter.

North Korea said on Saturday it was suspending nuclear and missile tests and scrapping its nuclear test site, and instead pursuing economic growth and peace.

The announcement came before the first North Korea-South Korea summit in more than a decade on Friday.

In a tweet minutes before he tempered enthusiasm about the North's statement, Trump interpreted it as a pledge to denuclearize: "Wow, we haven't given up anything & they have agreed to denuclearization (so great for World), site closure, & no more testing!"

However, Kim's announcement did not include a commitment to scrap existing nuclear weapons and missiles, and there are doubts he would ever give up the nuclear arsenal his country has been developing for decades. Kim said North Korea no longer needed to test nuclear bombs or missiles now that his country had the weapons.