The announcement came just after North Korean leader Kim Jong Un and South Korean President Moon Jae-in met in Pyongyang to announce they struck a deal to end military hostilities between the two nations and for North Korea to close a missile site and nuclear testing facility.
After two days of talks in Pyongyang, Moon and Kim on Wednesday signed a joint declaration to rid the Korean Peninsula of nuclear weapons, with the North inviting global observers to witness the dismantling of the Tongchang-ri missile test site.
Trump responded to news from the summit by saying he was "very excited", while Secretary of States Mike Pompeo said the United States was "prepared to engage immediately" with North Korea to move dialogue ahead.
Moon said he and Kim spent most of a three-day summit discussing how to break an impasse and restart nuclear talks between Pyongyang and Washington.
President Moon Jae-in and North Korean leader Kim Jong-un headed to Mt. Baekdu on the Chinese border on Thursday morning to climb the mythical birthplace of the Korean nation on the final day of Moon's visit. Compared to the vague language of their two earlier summits, Kim and Moon seem to have agreed on an ambitious program meant to tackle soaring tensions a year ago that had many fearing war as the North tested a string of increasingly powerful weapons.
It would be the first such trip by a North Korean leader since the Korean War ended in an armistice, leaving the peninsula divided and technically still in a state of war, and Moon said the historic journey could happen later this year. Moon's office says North Korean workers made a mistake.
"The spectacle of the South Korean president speaking to wildly cheering crowds of North Korean fans was one of the memorable moments of the Pyongyang summit", NPR's Rob Schmitz reports from Seoul.
While asking (for South Korea) to be the negotiator for the Pyongyang-Washington talks, he (Kim) vowed to cooperate for complete denuclearization. Although he has made a meaningful gesture of goodwill in returning US troops' remains from the Korean War, the evidence that Kim has begun the denuclearization process in earnest is messy at best.
"There is nothing the North has offered so far that would constitute irreversible movement toward denuclearisation, however you define that, by January 2021 or any other time, or even a reduction of the military threat it poses to the South and the region", said a U.S. intelligence official.
The sudden revival of diplomacy followed weeks of doubts in US President Donald Trump's administration's about whether North Korea was willing to negotiate in good faith after a June summit between Trump and Kim yielded few tangible results.
The North Korean leader on Wednesday agreed to shutter the Tongchang-ri missile-testing site in the presence of global observers, a move the USA welcomed by saying it was ready for immediate talks aimed at denuclearising the North. Pompeo had been expected to meet with North Korean officials last month.
The two leaders also agreed to pursue a bid to co-host the 2032 Olympic Games, and Moon said he expects Kim Jong-un to soon become the first North Korean leader to ever visit Seoul. The alternative-the horrors of nuclear, chemical, and biological warfare that an invasion of North Korea would unquestionably entail-is unthinkable.
"This will mark the beginning of negotiations to transform U.S. -DPRK relations through the process of rapid denuclearization of North Korea, to be completed by January 2021, as committed by Chairman Kim, and to construct a lasting and stable peace regime on the Korean Peninsula".
For its part, Pyongyang - which wants a formal declaration the 1950-53 Korean War is over - has condemned demands for its unilateral disarmament as "gangster-like".