South Korean President Moon Jae-in says he's been told by North Korean leader Kim Jong-un that he wants the US secretary of state to come to Pyongyang for nuclear talks.
Kim also wants a second summit with President Donald Trump as soon as possible, Moon said.
Moon was briefing reporters on Thursday after returning to Seoul after a three-day summit in Pyongyang with the North Korean leader.
Moon says he will carry a private message from Kim for Trump when he meets the US president in New York next week at a UN meeting.
Moon also said he would convey to Trump his and Kim's desire to get a declaration ending the Korean War by the end of this year.
The 1950-53 war still technically continues because it ended with a ceasefire not a peace treaty.
Such a declaration would be the first step toward a formal peace treaty, but the US is worried it could result in Kim pushing for the removal of US troops from South Korea.
In Pyongyang, Moon and Kim struck a set of agreements that included some North Korean disarmament steps that experts say won't satisfy US demands.