To some, including Mr. Moon, the South Korean leader, the summit meeting was a success even if many questions remained unanswered. Mr. Moon and others saw it as the clearest signal yet that the two countries were walking away from the brink of war and were willing to take bold steps to end decades of hostility.
In the weeks leading up to the meeting, North Korea suspended nuclear and missile tests, released three American hostages and disabled its only known nuclear test site. Mr. Kim agreed on Tuesday to help the United States find and bring home the remains of Americans from major Korean War battle sites in the North.
But the agreement signed on Tuesday lacks any detail on the central issue, denuclearization, raising fears among analysts that once negotiators wade into the specifics, the talks could end in stalemate, as they have after past nuclear disarmament accords. South Korean officials hope that the two strong-willed leaders will push the process ahead, with an eye on their legacies.
Mr. Kim needs to improve ties with Washington and lift sanctions if he wants to keep his promise to develop North Korea’s economy. Mr. Trump, meanwhile, has repeatedly boasted that he would resolve a problem his predecessors could not. He appears to believe that his willingness to engage the once-hermetic Mr. Kim in the global spotlight will encourage him to shed his isolation and denuclearize.
“President Obama said that North Korea was our biggest and most dangerous problem,” Mr. Trump said Wednesday on Twitter. “No longer — sleep well tonight!”
Mr. Trump has recently begun to acknowledge that denuclearization could take time, but he appears eager for it to start quickly. He said on Tuesday that Mr. Kim had promised to dismantle a facility for testing missile engines. In an interview with ABC News, Mr. Trump also said North Korea planned to “get rid of certain ballistic missile sites and various other things.” As of Wednesday, there had been no announcement from North Korea about removing such facilities.
“The critical question is what comes next?” Kelsey Davenport, nonproliferation policy director at the Washington-based Arms Control Association, said in an email. “The true test of success is whether the follow-on negotiations can close the gap between the United States and North Korea on the definition of denuclearization and lay out specific, verifiable steps that Pyongyang will take to reduce the threat posed by its nuclear weapons.”