"We hope that Chairman Kim will deploy his team. Representative (for North Korea) Biegun said we can continue the dialogue so that we can ultimately achieve what those two leaders set up back in Singapore in summer of last year," the secretary added.

Washington's top diplomat went on to say, "I am optimistic that that will happen before too long, and we are looking forward to the chance to reconnect with them in a formal way diplomatically."

Pompeo also made an apparent reference to the absence of his North Korean counterpart, Ri Yong-ho, at the ASEAN gathering.

"I regret that (it) looks like I am not going to have an opportunity to do that (talk with the North) while I am here in Bangkok," he said. "But we are ready to go."

Following the DMZ summit, Washington and Pyongyang were expected to resume their working-level talks around the middle of July.

Clouding the prospects for the resumption of the talks, the North recently fired off short-range ballistic missiles into the East Sea in an apparent protest against the plan by Seoul and Washington to stage a combined military exercise. (Yonhap)