Chung Eui-yong, South Korea's presidential security adviser, is set to arrive in Seoul on Sunday after his two-day visit to the United States apparently aimed at facilitating denuclearization talks between Washington and Pyongyang.

After arriving in Washington on Friday, Chung held talks with his counterpart John Bolton possibly over a range of issues such as how to maintain the current momentum for dialogue with the communist state amid reports on a lack of progress in the North's denuclearization.

"I am ready to return (home after) meeting (Bolton) well," he told Yonhap News Agency at Washington Dulles International Airport before departing for Seoul, while parrying questions about details of his meeting with Bolton.

His visit came as Seoul is revving up efforts to keep Washington and Pyongyang on track to enforce their June 12 summit agreement to build new relations, make joint efforts to establish a "lasting and stable" peace regime, and pursue the complete denuclearization of the peninsula.

A lack of any tangible progress on the denuclearization front, along with US President Donald Trump's talk of "no rush," has spawned worries that peace efforts could lose steam.

South Korean President Moon Jae-in has weighed in, saying during his Singapore visit on July 13 that the leaders of the US

and North may face "grave judgment" from the international community should they fail to deliver on their summit agreement.

The North has reportedly demanded discussions with the US

over formally ending the 1950-53 Korean War that was halted only with a truce, while the US apparently wants the reclusive state to agree to a specific denuclearization method and timetable. (Yonhap)