"I don't even want to use the term "maximum pressure" anymore", Trump added, referencing his preferred term for the punishing US economic sanctions imposed on North Korea in response to its nuclear and ballistic missile tests.
Asked about the North's willingness to abandon their nuclear weapons program, Trump said Pyongyang was open to the idea.
Plans for the high-stakes sit-down in Singapore had been cast into doubt.
"If the meeting does occur, they may get a breakthrough or they may not get a breakthrough", he said.
The White House confirmed later in the day that he had indeed eventually read the letter.
"We'll be, uh, meeting on June 12th in Singapore".
Kim Yong Chol has featured on lists of North Korean officials targeted by US Treasury sanctions, including for supporting his country's nuclear and missiles programmes and proliferation of weapons of mass destruction and the cyber attack.
North Korea's entourage has apparently chosen the Fullerton as its preferred venue.
"It's very unknown territory right now, because Kim Jong Un is fierce", Kim said.
Kim Yong Chol was greeted at the White House by chief of staff John Kelly and then whisked into the Oval Office. We did discuss that, the ending of the Korean War.
While the reporters said yes to the question they also discovered for the umpteenth time how much Trump lies.
Trump also said he viewed the Pompeo talks as a positive step, and that he "looks forward" to seeing what the letter says.
Trump and Pompeo walked Kim Yong Chol to his auto.
Mr Trump said the June 12 meeting would be "a beginning".
President Trump's remarks follow months of pressure from China and South Korea on Washington to invest in the economic reconstruction of North Korea, ravaged by almost a century of oppressive communist rule. He was granted special permission to travel to the USA for meetings this week with U.S. officials, the State Department said.
USA troops have been stationed in South Korea since a 1953 armistice that left the two Koreas technically still at war.
President Donald Trump has been caught lying to the media about pertinent issues time and again.
Kim is under U.S. sanctions for his alleged role in North Korea's nuclear weapons program and other illicit activities, including the 2010 sinking of a South Korean warship that killed 46 sailors.
Trump views a summit as a legacy-defining opportunity to make a nuclear deal.
Kim Yong-chol, the top North Korean to enter the White House in almost two decades, traveled from NY following two days of meetings with US Secretary of State Mike Pompeo on a possible summit between their leaders. "We don't know for sure whether the planned summit will produce tangible results that North Korea and the USA will be satisfied with". He was granted special permission to travel outside the NY area in order to meet with the president.