Seoul holds a ceremony marking the first anniversary of Pyongyang summit, but Pyongyang remains silent.

Axar.az reports citing NK News that North Korean officials did not attend Thursday`s ceremony, hosted by the South Korean government at the Office of Inter-Korean Dialogue in Seoul. But despite a now months-long impasse in dialogue, Kim said all countries involved in diplomacy “value the opportunity [for dialogue] and to continue their efforts to solve problems.”

He also urged North Korea and the U.S. to seize this window of opportunity, pointing to first vice foreign minister Choe Son Hui’s September to hold working-level negotiations at the end of the month.

“They should no longer delay [dialogue],” Kim told around 100 attendees at the ceremony.

Diplomat Lee Do-hoon is set to meet with his U.S. counterpart this week.