US Secretary of State Mike Pompeo announced progress in connection with Pyongyang’s denuclearization.

His remark came after talks with North Korean leader Kim Jong-un in Pyongyang, AP reported.

After the talks, Pompeo arrived in Seoul. He tweeted that he had a "good trip" and that he and Kim "continue to make progress on agreements made at Singapore summit," referring to the historic June meeting between Trump and Kim that resulted in a vague agreement for the North to denuclearize.

The meeting lasted about 3.5 hours. After landing in South Korea, he informed the national security adviser to the White House, John Bolton, and the chief of staff, John Kelly, about the visit.

The U.S. official who accompanied Pompeo said Sunday's meeting was "better than the last time," but added that "it's going to be a long haul."