US President Donald Trump expressed his hopes for the "success" of the next inter-Korean summit, Seoul said Tuesday, even as relations grow cooler between Washington and Pyongyang.
South Korean President Moon Jae-in is due to travel to Pyongyang later this month for what will be his third meeting with North Korean leader Kim Jong Un this year.
A high-level delegation will fly to the North Korean capital on Wednesday to discuss the details of Moon's visit.
In a phone conversation on the eve of the delegation's trip, Trump and Moon agreed to continue "close cooperation" in their efforts to denuclearise the North, Moon's office said in a statement.
"President Trump said he sincerely hoped for the success of the South-North summit in September, not only for the improvement of inter-Korean ties but also the implementation of the June 12 US-North Korea summit agreement and future dialogue," it added.
The two leaders also discussed holding a bilateral meeting on the sidelines of the upcoming UN General Assembly in New York later this month.
Moon and Kim have met face-to-face twice now, the first during a historic summit at the border truce village of Panmunjom in April.
They met a second time at the same location in May as they scrambled to salvage plans for a summit between Kim and Trump in Singapore, which eventually went ahead as scheduled.
The rapid rapprochement on the Korean peninsula led to a landmark meeting between Kim and Trump in June after months of trading threats of nuclear war amid heightened tensions.
At the summit the pair reached a vague agreement to work towards the "complete denuclearisation of the Korean peninsula", but there has been little movement since.
Pyongyang has slammed the US for its "gangster-like" demands for complete, verifiable and irreversible disarmament, and the UN's International Atomic Energy Agency reported there was no indication the North had stopped its nuclear activities.
Last month Trump ordered Secretary of State Mike Pompeo to abruptly cancel a planned trip to Pyongyang, citing lack of progress on denuclearisation.