Chinese President Xi Jinping told South Korea’s Lee Jae Myung on Saturday that he was willing to widen cooperation and jointly tackle challenges, while Lee sought Beijing’s help in efforts to resume talks with nuclear-armed neighbour North Korea.

Lee hosted Xi at a state summit and dinner after an Asia-Pacific leaders’ forum in the South Korean city of Gyeongju, Xi’s first visit to the U.S. ally in eleven years.

Beijing attaches great importance to relations with Seoul and sees South Korea as an inseparable cooperative partner, Xi said ahead of the summit, Lee’s office said in a statement.

Lee, who was elected in a snap election in June, has promised to strengthen ties with ally the United States while not antagonising China and seeking to lower tension with the North.

“I am very positive about the situation in which conditions for engagement with North Korea are being formed,” Lee said, referring to recent high-level exchanges between China and North Korea.

“I also hope that South Korea and China will take advantage of these favourable conditions to strengthen strategic communication to resume dialogue with North Korea.”

Lee has called for a phased approach to denuclearising North Korea, starting with engagement and a freeze on further development of nuclear weapons.

In a statement on Saturday, Pyongyang, a military and economic ally of China, dismissed the denuclearisation agenda as an unrealisable “pipe dream”.