North Korean leader Kim Jong-un has invited Donald Trump to meet him, an unprecedented overture which the US leader has said he will accept.
The shock announcement that a meeting could take place as early as May was made by South Korean officials in Washington.
They passed a verbal message from Mr Kim to Mr Trump and said North Korea’s leader “committed to denuclearisation”.
South Korea’s President Moon Jae-in said it was “a milestone for peace”.
“If President Trump and Chairman Kim meet following an inter-Korean summit, complete denuclearisation of the Korean Peninsula will be put on the right track in earnest,” he said.
South Korean National Security Adviser Chung Eui-yong, who earlier this week met Mr Kim in Pyongyang, announced the development after briefing Mr Trump at the White House.
North Korea has not yet issued any official comment on the week’s developments.
Mr Trump said the development was “great progress” but that sanctions on North Korea would remain in place until a firm agreement is reached.
His press secretary Sarah Sanders said they would meet “at a place and time to be determined”.
However analysts remain sceptical about what such rapidly arranged talks – normally the culmination of years of diplomacy – can achieve.
How did we reach this point?
North Korea has been isolated for decades because of its well-documented human rights abuses and its pursuit of nuclear weapons, in defiance of international laws.
It has carried out six nuclear tests, and has missiles which could reach the US. It says it needs these to ensure its survival.
But South Korea’s hosting of the Winter Olympics gave an unexpected window for diplomacy. Rare inter-Korean talks were held to facilitate the North’s carefully choreographed attendance.
South Korea then held landmark talks with Mr Kim in Pyongyang this week, returning home saying the North was willing to give up its nuclear weapons if it felt it had no reason to keep them.
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What has North Korea pledged?
There were four main elements to the statement:
- Mr Kim is prepared to sit down with the US president
- It is “committed to denuclearisation”
- It will halt all nuclear and missile tests
- It understands that US-South Korean military drills “must continue”.
The BBC’s Laura Bicker in Seoul says it is important to note that North Korea has not yet promised to abandon its nuclear weapons completely. It also remains unclear exactly what it is asking for in return.
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The North has halted missile and nuclear tests during previous talks before, only to resume when it lost patience or felt it was not getting what it demanded.
The last point is also significant. The US has had tens of thousands of military personnel in South Korea since the end of the Korean War. The massive annual joint war games infuriate the North, because it believes they are preparation for invasion.
They were due to take place during the Olympics but have been suspended for now.
Is this a victory for Trump?
Mr Trump has repeatedly belittled Kim Jong-un, and last year threatened him with “fire and fury” if North Korea continued to threaten the US. He has at times said there is no point in talking to North Korea.
But Mr Chung made a point of saying it was Mr Trump’s “maximum pressure policy” which had brought the parties to this point, a gesture which the president is likely to appreciate.
Our correspondent says Kim Jong-un has also scored a propaganda win, first with the Olympics and now by being seen to reach out to the US.
What about the other major players?
The South’s statement also credited “international solidarity” for reaching this point.
That is likely in part a reference to international sanctions, which have increased with each North Korean show of force.
China, North Korea’s main economic supporter, has in recent months toughened up its dealings with the North, including on key areas like petroleum and oil. This is thought to be putting a major strain on the North.
It has consistently pushed for all parties to talk so will welcome this development.
Japan, which saw North Korean missiles fly over its territory twice last year, welcomed news of a Trump-Kim meeting.
But Prime Minister Shinzo Abe said Japan would “keep putting maximum pressure until North Korea takes concrete actions toward denuclearisation”.
Have talks like this happened in the past?
No sitting US president has ever met a North Korean leader, but there have been repeated attempts to get North Korea to denuclearise.
The last major effort – the Six Party talks – collapsed in 2008, largely because North Korea refused to allow inspectors to verify that it had shut down its nuclear programme.
A number of bids to restart the talks also collapsed, including in 2012 when North Korea launched another rocket, two weeks after announcing a “leap day” agreement with the US.