At their first summit in more than a decade on Friday, the leaders of North and South Korea held hands, planted a tree, and signed a pledge to pursue peace on the peninsula.

The heavy symbolism of the night was the culmination of more than three months of efforts by both Koreas to change the political tone after last year's missile tests and military threats.

What that change of tone means for the prospect of long-term peace on the peninsula is still an open question. Analysts say South Korean President Moon Jae-in and North Korean leader Kim Jong Un will have to nurture the reduced tensions into concrete moves.

Sceptics view Kim's overtures as a duplicitous attempt to buy time, while others argue any real peace deal requires talking to the North Koreans.

Many of the thorniest issues, however, can't be solved by the two Koreas alone, leaving their leaders to focus on inter-Korean relations while trying to set the stage for Kim's expected summit with US President Donald Trump.

"This summit was just spadework, preparation for the North Korea-US summit to happen in the near future," said Kim Seung-hwan, a senior associate at the Centre for Strategic and International Studies. "That is the main game."

The coming weeks will be a busy time for South Korean officials.

Moon may meet with Trump before the US president's summit with Kim, and the South Korean president is also expected to meet with his Japanese and Chinese counterparts at a trilateral summit in early May.

South Korean officials will continue to closely coordinate with the Americans, and Moon will provide details of his meeting with Kim, said Moon Chung-in, a special adviser to Moon for foreign affairs and national security.

"Moon will be collecting information for Trump when he visits Washington in mid-May," he said. "Our government has come up with a comprehensive roadmap and we've been sharing that roadmap with the US"

While some observers criticized Friday's joint declaration for being light on specifics, others said outside countries like the United States and China needed to be involved in decisions on denuclearisation or a peace deal.

"There were important optics and symbols that can be built upon and the two leaders did some necessary things," said Andray Abrahamian, a research fellow at Pacific Forum CSIS. "They left the nuclear issue vague, which was the right thing to do. Moon has teed it up; let's see if Trump can carry it across the line."

INTER-KOREAN RELATIONS

Trump has taken credit for Kim's sudden willingness to talk, and Moon has also praised the American president's campaign of "maximum pressure" and sanctions for helping.

Much of the change in tone from confrontation to engagement has been driven by the two Korean leaders, however, starting with Kim's New Year's address, in which he said he was open to reducing tensions with South Korea and was willing to send a delegation to the Winter Olympics.

The Moon administration quickly responded, sparking a flurry of diplomatic visits and cross-border exchanges. It was South Korean officials who conveyed Kim's invitation to meet with Trump, and they helped arranged CIA Director Mike Pompeo's trip to Pyongyang.

Days before Friday's summit, Kim said North Korea would suspend nuclear and long-range missile tests and dismantle its only known nuclear test site.

"The shift to dialogue was made possible in the first instance by North Korea’s decision to engage with South Korea at the beginning of 2018, and from there, thanks in no small part to Moon Jae-in's deft diplomacy," Christopher Green, a senior adviser at International Crisis Group wrote in a report on Friday.

With the major inter-Korean engagements at the Olympics and the summit over, the two countries say they will deepen their engagement.

As part of efforts to reduce tensions, North and South Korea agreed to open a liaison office, stop propaganda broadcasts and allow divided families to meet.

Moon and Kim have also agreed to stay in close communication; Moon plans to visit Pyongyang later this year.