South Korea’s President Moon Jae-in and U.S. President Donald Trump hope to discuss North Korea on the sidelines of the U.N. General Assembly in New York this month, Moon’s office said on Tuesday, amid lacklustre progress on the North’s nuclear issues, Reuters reported.

Moon and Trump spoke for 50 minutes by telephone on Tuesday, a day before Moon’s special envoys were due to visit Pyongyang to discuss a third summit later this month between the liberal South Korean leader and his North Korean counterpart.

Moon and Trump agreed in their call “to explore the idea of meeting in person on the margins of the U.N. General Assembly and having in-depth consultations on strategies and how to cooperate on the peninsula issues,” Moon’s office said in a statement.

Kim vowed during his unprecedented summit with Trump in April in Singapore to work toward complete denuclearisation of the Korean Peninsula, but the two sides have since made little headway towards that goal.