"The White House pre-advance team for Singapore will leave as scheduled in order to prepare should the summit take place," Sanders said.
Moon and Kim met at Panmunjom, the truce village in the demilitarised zone and the site of their first meeting in April. The two met on the northern side of the line.
As a part of the rapprochement in advance of their April meeting, the two sides set up a direct phone line to improve communications and de-escalate any potential problems with direct dialogue.
However, the two leaders spoke face to face.
The Blue House's abrupt announcement of the two leaders' meeting stood in stark contrast to the highly choreographed summit in April.
At the meeting, the two leaders also discussed a successful implementation of the inter-Korean "Panmunjom Declaration." The two signed the three-page agreement at their earlier meeting, stating that "South and North Korea confirmed the common goal of realising, through complete denuclearisation, a nuclear-free Korean Peninsula," officials said.
Moon is scheduled to announce more details of the meeting.
Moon was blindsided by Trump's decision to abruptly announce he was cancelling the summit, less a day after returning from meeting in the Oval Office designed to keep the momentum in the diplomatic effort.
But the South Korean President seems to be tackling the latest difficulties with new resolve.
"Moon Jae In is acting decisively to keep his people safe from war," said Adam Mount, a nuclear expert at the Federation of American Scientists. "The US summit should have this objective, but Moon will fall back on the Panmunjom process if necessary," Mount said, referring to the inter-Korean agreement signed on April 27.
South Korea and the United States should work together to stop Kim from separating the diplomatic tracks and being able to "triangulate between the allies," Mount said. "It gives him added leverage over both. It is critical the alliance maintains a joint position on negotiations."
The North Korean leader's sister, Kim Yo Jong, awaited Moon's motorcade on the north side of the demilitarised zone, according to video clips of Moon's arrival released by the Blue House.
Once he arrived, he shook hands with Kim Yo Jong and walked down a red carpet as members of the North Korean military saluted. Moon then walked inside and shook hands with Kim Jong Un and posed for a photo in front of a large landscape painting, video clips show.
Moon and Kim were joined by South Korean intelligence chief Suh Hoon, who served as presidential envoy to North Korea, and Kim Yong Chol, senior North Korean official in charge of relations with South Korea, video clips show.
Kim and Moon ended the meeting in an embrace.
