GOYANG, South Korea (AP) — The leaders of North and South Korea played it safe Friday, repeating a previous vow to rid the Korean Peninsula of nuclear weapons but failing to provide any specific new measures or forge a potential breakthrough on an issue that has captivated and terrified many since the rivals seemed on the verge of war last year.

In a sense, the vague joint statement produced by North Korean leader Kim Jong Un and South Korean President Moon Jae-in to achieve “a nuclear-free Korean Peninsula through complete denuclearization” kicks one of the world’s most pressing issues down the road to a much-anticipated summit between Kim and U.S. President Donald Trump in coming weeks.

Even so, the Koreas’ historic summit Friday might be remembered as much for the sight of two men from nations with a deep and bitter history of acrimony holding each other’s hands and grinning from ear to ear after Kim walked over the border to greet Moon, and then both briefly stepped together into the North and back to the South.

Standing at a podium next to Moon after the talks ended, Kim faced a wall of cameras beaming his image live to the world and declared that the Koreas are “linked by blood as a family and compatriots who cannot live separately.”

What happened Friday should be seen in the context of the last year — when the United States, its ally South Korea and the North threatened and raged as the North unleashed a torrent of weapons tests — but also in light of the long, destructive history of the rival Koreas, who fought one of the 20th century’s bloodiest conflicts and even today occupy a divided peninsula that’s still technically in a state of war. Kim’s single step across the cracked, weathered concrete marking the Koreas’ border made him the first ruler of North Korea to step on South Korean soil since the war.

It marks a surreal, whiplash swing in relations for the countries, from nuclear threats and missile tests to intimations of peace and cooperation. Perhaps the change is best illustrated by geography: Kim and Moon’s historic handshake and a later 30-minute conversation at a footbridge on the border occurred within walking distance of the spot where a North Korean soldier fled south in a hail of gunfire last year, and where North Korean soldiers axe-murdered two U.S. soldiers in 1976.

The latest declaration between the Koreas, Kim said, should not repeat the “unfortunate history of past inter-Korean agreements that only reached the starting line” before becoming derailed.

Trump tweeted later Friday, “KOREAN WAR TO END!” and said the United States “should be very proud of what is now taking place in Korea!” Both Koreas agreed to jointly push for talks this year with the United States and also potentially China to officially end the Korean War, which stopped with an armistice that never ended the war.

Many will be judging the summit based on the weak nuclear language. North Korea’s nuclear and missile tests last year likely put it on the threshold of becoming a legitimate nuclear power. The North, which has spent decades doggedly building its bombs despite crippling sanctions and near-constant international opprobrium, claims it has already risen to that level.

South Korean conservative politicians criticized the joint statement as letting North Korea off the hook by failing to secure a clear commitment on nuclear disarmament. Liberty Korea Party Chairman Hong Joon-pyo denounced the summit as a “show camouflaged as peace.”

But the Koreas made inroads on a raft of other points of friction between them. Moon agreed to visit Pyongyang, North Korea’s capital, sometime in the autumn, and both leaders said they’d meet on a regular basis and exchange calls via a recently established hotline.

They agreed to settle their disagreement over their western maritime border by designating it as a peace area and securing fishing activities for both countries. They said they’d open a permanent communication office in the North Korean border town of Kaesong and resume temporary reunions of relatives separated by the 1950-53 Korean War.

“I feel like I’m firing a flare at the starting line in the moment of (the two Koreas) writing a new history in North-South relations, peace and prosperity,” Kim told Moon as they sat at a table, which had been built so that exactly 2018 millimeters separated them, to begin their closed-door talks. Moon responded that there were high expectations that they produce an agreement that will be a “big gift to the entire Korean nation and every peace-loving person in the world.”

Kim acknowledged the widespread skepticism over their summit. “We have reached big agreements before but were unable to fulfill them. … There are skeptical views on whether the meeting today will yield meaningful results,” Kim said. “If we maintain a firm will and proceed forward hand in hand, it will be impossible at least for things to get worse than they are now.”

Kim, during their talks, joked that he would make sure not to interrupt Moon’s sleep anymore, a reference to the North’s drumbeat of early-morning missile tests last year, according to Moon’s spokesman, Yoon Young-chan. Kim also referred to a South Korean island that North Korea attacked with artillery in 2010, killing four, saying the residents of Yeonpyeong Island who have been living in fear of North Korean artillery have high hopes the summit will help heal past scars. Kim said he’d visit Seoul’s presidential Blue House if invited.

The historic greeting of the two leaders, which may be the images most remembered from the summit, was planned to the last detail, though the multiple border crossings may have been impromptu. As thousands of journalists, who were kept in a huge conference center well away from the summit, except for a small group of tightly controlled pool reporters at the border, waited and watched, Moon stood near the Koreas’ dividing line, moving forward the moment he glimpsed Kim, dressed in dark, Mao-style suit, appearing in front of a building on the northern side. They smiled broadly and shook hands with the border line between them. Moon then invited Kim to cross into the South, and, after Kim did so, Moon said, “You have crossed into the South, but when do I get to go across?” Kim replied, “Why don’t we go across now?” and then grasped Moon’s hand and led him into the North and then back into the South.

Moon then led Kim along a blindingly red carpet into South Korean territory, where two fifth-grade students from the Daesongdong Elementary School, the only South Korean school within the DMZ, greeted the leaders and gave Kim flowers. An honor guard stood at attention for inspection, a military band playing traditional Korean folk songs beloved by both Koreas and the South Korean equivalent of “Hail to the Chief.”

They then took a photo inside the Peace House, where the summit took place, in front of a painting of South Korea’s Bukhan Mountain, which towers over the South Korean Blue House presidential mansion and where dozens of North Korean commandos trying to assassinate the then-dictator in Seoul were killed in 1968. Kim’s sister, Kim Yo Jong, was by Kim’s side throughout the ceremony, handing him a pen to sign a guestbook, taking the schoolchildren’s flowers from his hand and scribbling notes at the start of the talks with Moon.

Expectations were generally low on the nuclear issue, given that past so-called breakthroughs on North Korea’s weapons have collapsed amid acrimonious charges of cheating and bad faith. Skeptics of engagement have long said that the North often turns to interminable rounds of diplomacy meant to ease the pain of sanctions — giving it time to perfect its weapons and win aid for unfulfilled nuclear promises.

Advocates of engagement, however, say the only way to get a deal is to do what the Koreas tried Friday: Sit down and see what’s possible.

The White House said in a statement that it is “hopeful that talks will achieve progress toward a future of peace and prosperity for the entire Korean Peninsula. … (and) looks forward to continuing robust discussions in preparation for the planned meeting between President Donald J. Trump and Kim Jong Un in the coming weeks.”