TOKYO — Kim Jong Un's historic call for peace also included an unspoken message to President Trump: North Korea won't surrender its nuclear weapons easily.
The agreement Kim reached Friday with South Korean leader Moon Jae-in promised "a new era of peace" and sought a formal end to the seven-decade-old Korean War. While it said both countries are committed to a nuclear-free Korean Peninsula, it gave no details on concrete steps to achieve it.
More ominously, North Korean's state-run media released a commentary shortly after the agreement was announced calling on the United States to drop its "anachronistic hostile policy" and "bad manners."
The commentary declared North Korea a "world-level" political and military power, and said it would contribute to creating "a world without nuclear weapons."
But as a condition for dismantling its nuclear weapons program, North Korea has demanded a peace treaty officially ending the war and making it a recognized nation. It is also expected to seek an end to economic sanctions, and possibly removal of US nuclear weapons that defend South Korea and Japan.
"If North Korea gets a deal with the United States that serves their interests, they would be happy with that," said Mintaro Oba, a former State Department official who worked on North Korean issues. "But in the event that things fall apart, they want to be able to blame the United States and alienate it from its South Korean ally in the process."
Trump expressed optimism on Friday — even declaring "Korean War to end!" — but simultaneously sounded a note of caution. "Good things are happening, but only time will tell!" he said on Twitter.
Friday was filled with unprecedented scenes, starting with Kim's step over the ankle-high concrete slab dividing the Korean Peninsula — and then his walk back across the border hand-in-hand with Moon.
Kim also called for frequent meetings between the leaders, which would be a major shift given only three summits have taken place since the war. And he capped it off with live remarks to reporters, something no other North Korean leader had done before.
"We will continue to make efforts so that this agreement doesn't repeat the bad history of the other North-South agreement," Kim said.
Now the attention turns to Kim's meeting with Trump in late May or early July. No date or place has yet been set for what would be the first-ever summit between leaders of North Korea and the United States.
Trump's optimism stems in part from Secretary of State Mike Pompeo's secret trip to North Korea over Easter weekend to meet with Kim. Earlier this month, the president said the visit "went very smoothly and a good relationship was formed" while hailing the merits of denuclearization.
But it will take work to turn Friday's statement into lasting change. Past negotiations have fallen apart over inspections, weapons tests, and disputes over economic aid.
It is also unclear what each side means by the word "denuclearization." Kim may insist that the United States must remove its nuclear assets that defend its allies South Korea and Japan.
"The commitment to 'complete denuclearization' is ambiguous, and subject to different interpretations," said Youngshik Bong, a researcher at Yonsei University's Institute for North Korean Studies in Seoul. "It can be interpreted as North Korea getting rid of all warheads, or North Korean demands on the US military in South Korea."
So far, it's not clear whether any of those sensitive topics have been discussed. Trump has vowed to maintain sanctions on North Korea until he gives up his nuclear weapons, raising questions over the sequencing of any disarmament.
The next few months are crucial. For all the warm words, Kim still claims to possess the capability to strike the United States with a nuclear weapon — and Trump has threatened war to stop him.
"Considering the level of North Korea's nuclear and missile capabilities now, the declaration today falls short of expectations," said Shin Beomchul, a director at the Asan Institute for Policy Studies who studies North Korea's military. "The two leaders left most of the details for denuclearization on Trump."
While the North Korean leader can still retreat from his peace pledge and go back into escalation mode at any time, Friday's overt friendliness with Moon could add an obstacle.
Every public message Kim sent Friday — including hugging, smiling, and handshaking — was viewed by the world, although the events were not broadcast live in North Korea.
As an entourage of North Koreans stayed behind, Kim approached the border that has divided North and South Korea for almost seven decades. On the South Korean side of that border — marked by a small barrier — Moon was waiting. Both shook hands, before Kim stepped into South Korea.
Kim then went off script, asking the South Korean leader to also step into North Korea.
Kim and Moon then walked off to North Korea hand in hand, where they stayed for some moments before returning and heading to Panmunjom, the so-called ''truce village.''
These images could go into history as a record of a day when tensions on the Korean Peninsula faded — or as a moment of false hopes.