Mr. Tillerson was an early advocate of diplomatic engagement with North Korea, pursuing it as part of his efforts to win the release of Americans detained there. But he often leaned too far ahead of Mr. Trump in his eagerness, most notably when the president publicly undercut him during one of Mr. Tillerson’s trips to Beijing, tweeting that he was “wasting his time trying to negotiate with Little Rocket Man.”

Mr. Pompeo, a hawkish former Army officer and Republican congressman who has spoken about the possibility of regime change in North Korea, is viewed as more skeptical about engaging with Mr. Kim. It is not clear whether he advised the president in advance of his decision to accept the invitation to talk. But he is an astute reader of Mr. Trump’s preferences, and even before his nomination as secretary of state had become a vocal defender of the meeting.

“President Trump isn’t doing this for theater,” he said last week on Fox News. “He’s going to solve a problem.”

North Korea has still not publicly confirmed the meeting, a silence that has raised suspicions among some Korea experts about whether Mr. Kim really made the offer — or if he did, whether he agreed to halt nuclear and missile tests, and put his nuclear arsenal on the table, as part of a negotiation with the United States.

On Friday, however, the White House appeared committed. Mr. Trump spoke with President Moon Jae-in of South Korea, who has pushed tirelessly for talks between North Korea and the United States, and reaffirmed his intention to meet Mr. Kim by the end of May.