WASHINGTON – President Donald Trump lost no time hailing the historic nature of Friday's meeting between the North and South Korean leaders. But the gauzy images and vows of peace by Kim Jong Un and his counterpart from the South, Moon Jae-in, have complicated Trump's task as he prepares for his own history-making encounter with Kim.

While the two Korean leaders pledged to rid the heavily armed peninsula of nuclear weapons, they put no timeline on that process, nor did they set out a common definition of what a nuclear-free Korea would look like. Instead, they agreed to pursue a peace treaty this year to formally end the Korean War after nearly seven decades.

The talk of peace is likely to weaken the two levers that Trump used to pressure Kim to come to the bargaining table. A resumption of regular diplomatic exchanges between the two Koreas, analysts said, will inevitably erode the crippling economic sanctions against the North, while Trump will find it hard to threaten military action against a country that is extending an olive branch.

To meet his own definition of success, Trump will have to persuade Kim to accept "comprehensive, verifiable and irreversible denuclearization" of North Korea — something Kim has shown no willingness to accept in the past, and few believe he will accede to in the future.

"This summit has put even greater expectations, greater hype and greater pressure on Trump," said Victor Cha, a Korea scholar at Georgetown University who was considered by the Trump administration to be ambassador to Seoul. "He hyped this meeting with his tweets, and now the entire focus is going to be on his negotiating prowess."

"This is a moment of his own making," Cha added.

No apparent anxiety

Characteristically, Trump betrayed no anxiety in recent days as he discussed the challenges of the summit meeting, which is scheduled for late May or early June in a location still to be determined. He took much of the credit for the diplomatic thaw on the Korean Peninsula, and he said he would not commit the mistakes of his predecessors, whom he said had showered the North with money and extracted nothing in return.

"The United States has been played beautifully, like a fiddle, because you had a different kind of a leader," Trump said after meeting with German Chancellor Angela Merkel at the White House. "We're not going to be played, OK? We're going to hopefully make a deal; if we don't, that's fine."

Trump reiterated that he was prepared to cancel the meeting, or walk out, if his diplomatic efforts were not making any headway. But some of his aides say privately they worry that the president, with an eye on the history books and a flair for the theatrical, is determined to emerge with a win, even if it falls short of his stated goals.

Certainly, he seemed beguiled by the imagery of the Moon-Kim meeting. "KOREAN WAR TO END!" he tweeted before 7 a.m. on Friday, a few hours after the leaders shook hands in the ­Demilitarized Zone.

On Saturday, Trump said he had a "very good talk" with Moon. "Things are going well," he tweeted. "Time and location of meeting with North Korea is being set." He also said he had briefed Japanese Prime Minister Shinzo Abe of Japan, who has watched the rush of diplomacy with some concern.

High price

The price of failure would be high for Trump. The U.S. could face a split with its ally South Korea, which is deeply invested in ending its estrangement from the North. Tensions could flare with China, North Korea's main trading partner, which only grudgingly signed on to the sanctions and would be likely to balk at keeping them in place if Kim is talking about peace.

There is little question, senior officials and analysts said, that the U.S.-led sanctions, combined with Trump's bellicose vows to rain "fire and fury" on North Korea if it threatened the American homeland, helped bring Kim to the table.

But Trump is only one of three actors in this drama, and perhaps not the most crucial one. Moon, a progressive former human rights lawyer, ran for office on a platform of conciliation with the North and has moved aggressively to deliver. He, not Trump, has set the pace and terms of the negotiation with the North, though U.S. officials say that Seoul is closely coordinating with Washington.

Kim, for his part, made a bold bet on diplomacy. His motives for seeking a rapprochement are open to debate. Skeptical analysts said the advancements in North Korea's intercontinental ballistic missile program — as much as sanctions or threatened military strikes — made the timing right for an overture. Others say he is replaying the cycle of provocation and conciliation pioneered by his father and grandfather.

Though Kim made gestures of his own — a pledge not to test bombs or long-range missiles, and an end to the North's longtime insistence that U.S. troops withdraw from the peninsula — he has not made any tangible concessions on his nuclear weapons. The language in his joint statement with Moon about denuclearization was both vague and familiar to veterans of past talks.

"He's gotten all these meetings with world leaders without making any concessions," said Jung Pak, a former CIA analyst who is a senior fellow at the Brookings Institution's Center for East Asia Policy Studies. "So far, everything has been no-cost for Kim."

Given the warmth of the Moon-Kim meeting, few analysts predict that Trump's meeting with Kim will be sour. The most likely scenario is an encounter that produces more riveting imagery and results in a broad agreement to negotiate disarmament in return for an easing of economic isolation.

North's insurance policy

With the North seeking to re-establish diplomatic and economic ties to the South, Trump will find it difficult to play the cards he used during his first year in office. Some analysts said Kim's outreach to Moon amounted to a kind of insurance policy against Trump.

"It becomes awfully hard for Trump to return to the locked-and-loaded, 'fire and fury' phase of the relationship," said Jeffrey Bader, a former Asia adviser to President Barack Obama.

Administration officials acknowledged the risk that Trump could find himself out of sync with Moon. They said their job was to remind the president of the proper sequence of negotiations with North Korea: tangible steps toward denuclearization, followed by an easing of sanctions, and then a treaty.

As always, though, the wild card is Trump. "He sees this as a Nixon-in-China moment, and he will want to move quickly, where patience is the order of the day," said Kurt Campbell, a former assistant secretary of state for East Asian affairs.