US President Donald Trump confirmed on Wednesday that his CIA chief has held secret talks with North Korea's leader in Pyongyang, as the South said it was exploring paths to a peace deal with the nuclear-armed North.
Seoul's push for discussions on formally declaring an end to inter-Korean hostilities was the latest in a series of diplomatic initiatives involving the divided Korean peninsula that would have been unthinkable just months ago.
The flurry of activity has raised hopes for a major breakthrough from a pair of upcoming and potentially historic summits.
The latest shock move was CIA director Mike Pompeo's face-to-face meeting with North Korea's young leader, reportedly during the first weekend in April.
"Mike Pompeo met with Kim Jong Un in North Korea last week. Meeting went very smoothly and a good relationship was formed. Details of Summit are being worked out now," Trump tweeted.
"Denuclearization will be a great thing for World, but also for North Korea!" he added, regarding efforts to persuade North Korea to abandon its nuclear weapons ambitions.
Kim is expected to meet South Korea's President Moon Jae-In at a landmark meeting next Friday where discussion of a peace declaration is now on the cards.
Trump earlier said that the summit could, with his "blessing," explore a peace treaty to formally end the conflict.
"We are looking at the possibility of replacing the armistice regime on the Korean peninsula with a peace regime," a senior official at South Korea's presidential Blue House said Wednesday.
"But this is not something we can do by ourselves. It needs close discussions with relevant parties including North Korea."
The 1950-53 Korean War ended in an armistice rather than a peace treaty, leaving the two sides technically at war. The Demilitarised Zone between them bristles with minefields and fortifications.
But reaching any final treaty would be fraught with complications.
"The peace treaty is a very difficult problem," said Koo Kab-woo, a professor at the University of North Korean Studies.
While the US-led United Nations command, China and North Korea are signatories to the decades-old armistice, South Korea is not.
Both Pyongyang and Seoul claim sovereignty over the whole Korean peninsula, but a treaty could imply mutual recognition of each other.
Trump himself plans to hold a summit meeting with Kim within the next two months.
The pair has not spoken directly, the White House said, but the US president revealed Tuesday there had been contact at "very high levels" to prepare for the historic meeting - an apparent reference to Pompeo's visit.
He also said that "five locations" were being considered for the summit with Kim.
"That will be taking place probably in early June or before that assuming things go well. It's possible things won't go well and we won't have the meetings and we'll just continue to go on this very strong path we have taken."
US officials say that no decision has yet been made on a meeting venue, but China, North Korea, South Korea, and Panmunjom in the Demilitarized Zone between the two Koreas are seen as possible locations.
Beijing is North Korea's sole major ally, an alliance dating back to the Korean War, but relations deteriorated after China supported United Nations sanctions to punish Pyongyang over its nuclear weapons programme.
The sudden talk of rapprochement on the Korean Peninsula has also sparked a flurry of diplomatic activity with Pyongyang's giant northern neighbour
Last month Kim made a surprise visit to Beijing to meet President Xi Jinping in what was believed to be the North Korean leader's first trip outside his isolated nation's borders since he succeeded his father in 2011.
Senior Chinese officials have since travelled to Pyongyang amid mounting speculation Xi might make a reciprocal visit.