South Korean President Moon Jae-in has said a three-way summit with North Korea and the United States is possible.
President Moon is planning a meeting with North Korean leader Kim Jong-un next month and US President Donald Trump has said he would meet Mr Kim by the end of May.
"A North Korea-US summit would be a historic event in itself following an inter-Korean summit", President Moon said at a preparatory meeting for the inter-Korean summit.
He said the series of summits should aim for a "complete end" to the nuclear threat on the Korean peninsula.
Meanwhile, North Korea has broken its silence on the diplomatic thaw with Washington and Seoul, saying it is driving the "peace offensive", rejecting suggestions that sanctions had forced it to the negotiating table.
The comment, from the North's official news agency KCNA, did not directly mention the summits but noted the "dramatic atmosphere for reconciliation" with the South and "a sign of change" with the US.
But it said Pyongyang's overtures came from a position of strength, not from weakness, even as it confronts intense international pressure as well as biting economic sanctions over its nuclear weapons programme.
