SEOUL, South Korea — When the South Korean president meets with President Trump in Washington next week, the two will discuss security assurances and economic incentives for a denuclearizing North Korea, following up on Mr. Trump’s reassuring words for the North’s young leader, a presidential aide in Seoul said on Friday.

At the White House meeting on Tuesday, President Moon Jae-in of South Korea hopes to advise Mr. Trump on the summit meeting planned on June 12 with the North Korean leader, Kim Jong-un, in Singapore. Mr. Moon, who had a dramatic meeting with Mr. Kim on the inter-Korean border on April 27, helped arrange the Singapore meeting.

As those talks near, however, North Korea has become increasingly disagreeable, threatening to cancel the event over fears that it will not get the rewards it is seeking in exchange for dismantling the nuclear arsenal the impoverished country has taken decades to build.

“The two heads of states will focus their discussions on detailed plans to achieve the complete denuclearization of North Korea and permanent settlement of peace on the Korean Peninsula,” Nam Gwan-pyo, a senior presidential aide to Mr. Moon, said on Friday of the White House meeting. “We expect them to discuss ways to guarantee a bright future for the North in return for its complete denuclearization.”