South Korean President Moon Jae-in and North Korean leader Kim Jong Un held an unannounced meeting on May 26 to discuss a possible upcoming summit between Kim and U.S. President Donald Trump, the South said.
It was the second inter-Korean summit in as many months.
The two met in the "truce village" of Panmunjom just north of the heavily militarized border, South Korea's presidential office said.
"The two leaders candidly exchanged views about making the North Korea-U.S. summit a successful one and about implementing the Panmunjom Declaration," South Korea's presidential spokesman said in a statement, referring to an April 2018 announcement in which both men pledged to work toward achieving peaceful and prosperous inter-Korean relations.
He did not confirm how the secret meeting was arranged.
Moon was due to announce details of the meeting with Kim early on May 27.
The surprise meeting came after U.S. President Donald Trump said the United States is having "productive talks" about reinstating a summit with Kim.
Trump's announcement came one day after he announced he was canceling the meeting.
Trump said in a Twitter post late on May 25 that the summit, if it does occur, will be on June 12 in Singapore as originally planned.
South Korea's presidential spokesman responded that "we are cautiously optimistic that hope is still alive for U.S.-North Korea dialogue."
Trump set off efforts to reschedule the summit after his decision to cancel on May 24, citing Pyongyang's "open hostility," prompted a conciliatory and contrite response from North Korea, which said it remained open to talks.
"It was a very nice statement they put out," Trump said at the White House. "They very much want to do it. We'd like to do it."
The White House said on May 26 that an advance team would leave for Singapore this weekend, as originally scheduled, to prepare for a possible summit there.
"The White House pre-advance team for Singapore will leave as scheduled in order to prepare should the summit take place," White House press secretary Sarah Sanders said.
The summit was originally scheduled in a surprise development after months of escalating threats and insults between the two leaders after North Korea's multiple tests last year of nuclear bombs and intercontinental ballistic missiles which it claimed were capable of reaching the U.S. mainland.
Just before Trump had called off the meeting, Pyongyang, in a carefully choreographed publicity effort, declared that it "completely" dismantled its only nuclear test site.
However, only a small group of international journalists handpicked by Pyongyang were invited to attend the demolition at the Punggye-ri site.
U.S. State Department spokeswoman Heather Nauert said on May 25 that Secretary of State Mike Pompeo and South Korean Foreign Minister Kang Kyung-wha reaffirmed their "shared commitment to the denuclearization of the Korean peninsula" and pledged to coordinate "in all of their efforts to create conditions for dialogue with North Korea."
U.S. Defense Secretary Jim Mattis said on May 25 that there was "possibly some good news" on the summit, while Sanders told reporters at the White House: "If the meeting takes place on June 12, we will be ready."