South Korea's top national security adviser visited Washington on Wednesday to meet with his U.S. counterpart, John Bolton, the White House said.
The surprise trip by Chung Eui-yong, head of the presidential National Security Office, came ahead of the South Korean and U.S. presidents' separate summits with North Korean leader Kim Jong-un.
South Korean President Moon Jae-in is set to meet with Kim on April 27, while U.S. President Donald Trump has said his meeting will be in May or early June.
A spokesperson for the White House National Security Council initially said Chung and Bolton met Wednesday but later corrected that the meeting will take place Thursday.
It will be their first encounter since the U.S. national security adviser took office.
"Ambassador Bolton started on Monday, and this is a courtesy call with his South Korean counterpart," the spokesperson told Yonhap on background.
The meeting was postponed due to Bolton's need to handle the U.S. response to the suspected chemical attack in Syria, according to sources.
Chung traveled to the U.S. capital last month shortly after his meeting with Kim in Pyongyang. He conveyed the North Korean leader's desire to hold a summit with Trump as soon as possible, along with his commitment to the denuclearization of the Korean Peninsula.
Trump accepted the invitation on the spot.
According to one source, Seoul expressed its wish to arrange a meeting between Chung and Bolton soon after the latter took office and to establish a direct communication channel between the two to coordinate preparations for the summits.
Chung's absence from Moon's publicly announced engagements Wednesday spurred speculation he may have left for the U.S.
The appointment of Bolton, known for his hawkish views, raised concern the U.S. could consider military action against Pyongyang should the summit go wrong. The former U.S. ambassador to the United Nations recently argued for a preventive strike on North Korea, although he also said it is not his favored option.
Seoul is adamantly against any armed conflict on the peninsula.
In Washington, South Korean Ambassador to the U.S. Cho Yoon-je and Susan Thornton, acting U.S. assistant secretary of state for East Asia, plan to hold regular summit-related meetings starting next week.
Trump also confirmed he is planning to go ahead with the Kim meeting.
"So much Fake News about what is going on in the White House," he tweeted. "Very calm and calculated with a big focus on open and fair trade with China, the coming North Korea meeting and, of course, the vicious gas attack in Syria. Feels great to have Bolton & Larry K on board."
Larry Kudlow is the new director of the National Economic Council.