Kim Jong Un and Moon Jae-in headed for the spiritual birthplace of the Korean nation Thursday for a show of unity after their North-South summit gave new momentum to Pyongyang's negotiations with Washington.
The North Korean leader on Wednesday agreed to shutter the Tongchang-ri missile-testing site in the presence of international observers, a move the US welcomed by saying it was ready for immediate talks aimed at denuclearising the North by January 2021.
Pyongyang also said it could dismantle its best-known nuclear facility at Yongbyon, if the US takes "corresponding measures", as Kim and the South Korean president held their third summit this year.
It is an important caveat, but the declaration appeared to break the logjam in nuclear discussions with Washington.
President Donald Trump welcomed the move, tweeting that Kim had "agreed to allow Nuclear inspections, subject to final negotiations", adding: "Very exciting!"
Secretary of State Mike Pompeo also praised the "important commitments", saying he spoke with his North Korean counterpart and invited him to meet next week on the sidelines of the United Nations General Assembly.
Negotiations had stalled since the historic Singapore summit between Trump and Kim in June, when Kim declared his backing for denuclearisation of the peninsula but no details were agreed.
Washington and Pyongyang have subsequently sparred over what that means and how it will be achieved, with the Trump administration consistently referring to the denuclearisation of North Korea specifically.
For its part Pyongyang has condemned demands for its unilateral disarmament as "gangster-like".
Experts remain sceptical, pointing out that Pyongyang has already said several times it has no need for further testing.
Moon and Kim have sought to strengthen the North-South relationship at their Pyongyang summit, agreeing that the North Korean leader will visit Seoul "at an early date".
Moon said the historic trip could happen later this year. It would be the first by a North Korean leader since the Korean War ended in a 1953 armistice, leaving the peninsula divided by the Demilitarized Zone and technically still in a state of war.
The two leaders also agreed to a open permanent facility for family reunions, work towards joining up road and rail links, and bid jointly for the 2032 Olympics.
On Thursday, Moon and Kim flew separately from Pyongyang to Samjiyon airport near Mount Paektu, media pool reports said.
Video footage showed Moon's motorcade passing through Pyongyang streets lined with crowds in their Sunday best, waving flags and flowers and chanting "Unification of the fatherland!"
The two drove from Samjiyon to Mount Paektu on the Chinese border, a Southern presidential spokesman told journalists.
The 2,744-metre (9,003-foot) peak is considered sacred to all Koreans as the birthplace of Dangun, the legendary founder of the first Korean kingdom.
According to Pyongyang's narrative, it is also said to be where Kim Il Sung, the country's founder and Kim Jong Un's grandfather, led his anti-Japanese guerilla campaign during the 1910-45 colonial rule.
South Korean tourists flock to see the mountain via China but only a handful of Southerners have been granted access from the North Korean side, mostly for research purposes.
After the excursion, Moon will fly directly back to Seoul, the spokesman added, ending his three-day visit to the North.