Top U.S. and North Korean officials met in the city Thursday in an effort to save a planned meeting between President Donald Trump and Kim Jong-un that is now in limbo.
Secretary of State Mike Pompeo met with North Korea's former military intelligence chief Thursday morning.
Pompeo tweeted that the talks were substantive and that they discussed their "priorities for the potential summit between our leaders.''
Trump also told reporters the talks were going well and that North Korean officials may come to Washington on Friday with a letter from Kim.
Trump canceled the planned June 12 summit last week, but then suggested it could still happen.
Wednesday, White House Press Secretary Sarah Huckabee Sanders said the administration is preparing for a sitdown on that date.
U.S. delegations have also been meeting with North Korean officials in Singapore and in the Korean Demilitarized Zone.