In preparing for the summit, Trump's administration has said it wants North Korea's "complete, verifiable, and irreversible denuclearization" but has offered few details of the strategy it will employ at the talks. -South Korean alliance, and also aligns with Kim's goals.
The U.S. now has 28,500 troops stationed in the country, and South Korea, a longtime ally, pays almost $890 million a year in expenses, or about half the total cost.
The NSC official gave the reassurance to South Korea's visiting top security adviser, Chung Eui-yong, who is in Washington for talks on the upcoming U.S.
For years President Trump has expressed his desire to withdraw USA troops from South Korea, arguing that our ally should be footing a much larger portion of the bill.
Mr Kim said at last week's summit that he would discuss details of denuclearisation at the North Korea-US summit, South Korea's Yonhap news agency said, citing South Korean Unification Minister Cho Myoung Gyon.
Word of Trump's plans follows a South Korean official's statement in which he suggested a potential peace treaty on the Korean Peninsula could render the current troops levels unnecessary.
South Korea was quick to deny the story.More news: São Paulo building collapses in huge blaze
On the rationale for drawing down USA troops in the region, Trump previously cited what he called "a very big trade deficit" with the South, and claimed "our allies care about themselves".
In a tweet Wednesday, the president said the previous administration has long asked for three US citizens to be released from a labor camp in North Korea, but it hasn't happened.
However, is it the right time for the U.S.to consider reducing its troop presence in South Korea?
"What will happen to U.S. forces in South Korea if a peace treaty is signed", special adviser Moon Chung-in said in an opinion column.
"But from the perspective of the U.S". -South Korean military exercises, Moon said last week that he'd dropped his demands for a USA exit in exchange for denuclearization.
A U.S. State Department spokeswoman said she could not confirm the reports. "It will be hard to justify their continuing presence".
The letter came amid reports that the White House was looking at Singapore and a facility inside the Korean peninsula's demilitarized zone as possible sites for Trump's anticipated meeting with Kim.