Media captionKorean leaders’ surprise "Hollywood" meeting
A US team is holding talks with North Korean officials to prepare a possible meeting between President Donald Trump and the North’s leader Kim Jong-un.
The talks in the village of Panmunjom, in the demilitarised zone between the two Koreas, is the latest sign that the summit could take place after all.
On Thursday Mr Trump called off the meeting – due in Singapore next month – citing the North’s "hostility".
But both sides have since been working to get it back on track.
On Saturday Mr Kim and South Korean President Moon Jae-in held an unannounced meeting. Mr Moon said the North’s leader had "again made clear his commitment to a complete denuclearisation of the Korean peninsula".
Mr Kim Jong-un later spoke of his "fixed will" that the summit should go ahead. Mr Trump said things were "moving along very nicely".
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The visit by the US delegation was first reported by the Washington Post later on Sunday. The team was led by Sung Kim, a former ambassador to South Korea, who was to hold talks with North Korean Vice-Foreign Minister Choe Son-hui, the newspaper said.
The state department confirmed that the two sides had met at the border. "We continue to prepare for a meeting between the president and North Korean leader Kim Jong-un," state department spokeswoman Heather Nauert said.
CNN said that the discussions were focused on the substance of the summit, while a separate US team in Singapore was dealing with the logistics.
The meeting would be the culmination of diplomatic efforts that began this year to defuse what had threatened to become a military confrontation between the nuclear-armed communist North and the South.
What came out of Saturday’s surprise talks?
It was the second meeting in as many months between the leaders of the two Koreas. Mr Moon said he and Mr Kim had "agreed that the 12 June summit should be held successfully".
But Mr Moon suggested Mr Kim was not certain whether Washington could guarantee the stability of his regime.
"What Kim is unclear about is that he has concerns about whether his country can surely trust the United States over its promise to end hostile relations," Mr Moon said.
North Korean state media said the two leaders had had a "candid dialogue" and that Mr Kim had called for co-operation to "establish a mechanism for permanent and durable peace".
The long-dreamed-of prize
Analysis by the BBC’s Rupert Wingfield-Hayes in Seoul
The pictures from the second summit between Kim Jong-un and Moon Jae-in show how dramatically the atmosphere has changed here on the peninsula.
Their first summit in April took months to arrange. On Saturday, they met just 24 hours after a phone call from Pyongyang.
It is significant that this second meeting was requested by Mr Kim. It is clear he really wants to salvage the Singapore summit. The question that remains is why?
President Trump’s supporters think Mr Kim is now desperate to find a way out of crushing economic sanctions. But the rhetoric from Pyongyang suggests Kim Jong-un believes his nuclear arsenal puts him in a much stronger position than his father or grandfather and, because of that, he is very close to grasping the long-dreamed-of prize, a face-to-face summit with a US president.
What needs to be sorted ahead of the summit?
There is still a lot of ground to be covered and Mr Trump has clearly shown that if he does not think a deal can be done, he will not go.
Media captionThe nuclear word Trump and Kim can’t agree on
It is unclear whether Mr Kim will agree to fully abandon his nuclear arsenal. Similar pledges in the past have not been upheld.
Analysts say the US had wanted denuclearisation first – followed by rewards in the form of lifted sanctions and economic aid.
Mr Kim has indicated he wants a phased approach, with his steps met by reciprocal ones from the US and the South – mainly on sanctions but also easing of the US military presence in South Korea.
Mr Trump has not ruled out such an incremental approach.
North Korea has been subjected to numerous rounds of international sanctions since 2006, which has cut off most of its exports and capped its imports of oil.
The North also wants assurances that its survival as a state would never be in question.
How did we get here?
Getting this far has been a surprise given that North Korea had maintained its strident rhetoric – and continued its nuclear and missile tests – through 2016 and 2017.
This brought a bitter war of words between Mr Trump and the North Korean leadership.
But a rapprochement began in January when Mr Kim suggested he was "open to dialogue" with South Korea.
Image copyrightEPAImage captionKoreans played under a unified flag at the Winter Olympics
The following month the two countries marched under one flag at the opening ceremony of the Winter Olympics, held in the South.
Mr Kim announced he was suspending nuclear tests and held his landmark summit with Mr Moon last month, where the pair agreed to work to rid the peninsula of nuclear weapons.
This week North Korea said it had dismantled its Punggye-ri nuclear test site, although scientists believe it partially collapsed after the last test in September 2017, rendering it unusable.