North Korean leader Kim Jong-un has invited Donald Trump to meet him, an invitation the US leader has said he will accept.
The shock announcement was made by senior South Korean officials in Washington, who passed on a letter from the North Korean leader.
They said Mr Kim had also agreed to halt nuclear and missile tests and was "committed to denuclearisation".
It appears to be a major breakthrough after months of threats and violence.
The South Korean delegation had held unprecedented talks with Mr Kim in Pyongyang earlier this week, part of a diplomatic thaw following the Winter Olympics in South Korea, then travelled to the US to pass on their message.
Mr Trump, who has previously said there is no point in talking to North Korea, said the development was "great progress".
But he said sanctions will remain in place until a firm agreement is reached.
'Refrain from nuclear tests'
South Korean National security adviser Chung Eui-yong, speaking outside the White House after meeting Mr Trump, credited the US president's "maximum pressure policy together" along with international solidarity for reaching this point.
"I told President Trump that at our meeting North Korean leader Kim Jong-un said he's committed to denuclearisation," Mr Chung told a news conference.
"Kim pledged that North Korea will refrain from any further nuclear or missile tests."
He added: "President Trump appreciated the briefing, and said he would meet Kim Jong-un by May to achieve permanent denuclearisation."
North Korea has been isolated on the international stage for decades because of its well-documented human rights abuses and its pursuit of nuclear weapons, in defiance of international laws.
No sitting US president has ever sat down for talks with a North Korean leader, so such a meeting would be diplomatically seismic.
But the BBC's Laura Bicker in Seoul says it is important to note that North Korea has not yet said it will abandon its nuclear weapons, just that it is committed to doing so.
Kim Jong-un has scored a propaganda win, she adds, but Mr Trump will also feel like a winner, with his fiery policies credited for bringing the parties to the table.
He has repeatedly belittled Kim Jong-un, and last year threatened him with "fire and fury the likes of which the world has never seen before" if he continued to threaten the US.
It also remains unclear exactly what North Korea is asking for in return for these talks, says our correspondent.