NEW YORK — President Trump said Monday he expects to meet North Korean leader Kim Jong Un “quite soon,” expressing optimism that his efforts to negotiate a denuclearization deal are still on track.

Trump told reporters here at the U.N. General Assembly that the talks are “moving very well” and that the two sides are making “tremendous progress,” even though he had abruptly canceled a visit from Secretary of State Mike Pompeo to Pyongyang earlier this month.

“We have many things in store,” Trump said. He noted Kim had sent him a letter requesting a second meeting. “We’ll be doing that,” he said.

Trump has alternated between optimism and frustration since his historic June summit with Kim in Singapore, where the two sides announced plans to work toward a general goal of denuclearizing the Korean Peninsula. But that agreement lacked details, and the Trump administration has grown impatient with the Kim regime’s lack of engagement.

U.S. intelligence agencies have said that North Korea, which has not tested a ballistic missile since agreeing to the summit months ago, continues to work on technical advancements in its nuclear arsenal in secret.

But the tone has warmed again since Kim met last week with South Korean President Moon Jae-in, who made his first visit to Pyongyang. Moon said Kim pledged to work toward denuclearization by 2021, which would mark the end of Trump’s first term.

Trump’s remarks marked a sharp shift since a year ago, when he used his maiden speech at the United Nations to warn North Korea over its nuclear program and said Kim was on a “suicide mission.”

“Since we got here, it’s a different world,” Trump said Monday. “This is one year later, a very different time.”

Trump is scheduled to meet with Moon on Monday afternoon to discuss security and trade issues.