North Korean leader Kim Jong-un and South Korean President Moon Jae-in are meeting at their mutual border.
Kim has crossed over to the southern side, the first North Korean leader to do so since the end of the Korean War.
They will discuss North Korea's indications it could be willing to give up its nuclear weapons.
North Korea has been isolated for decades because of its nuclear and weapons programme and its dismal human rights record.
The meeting could pave the way for Kim to meet US President Donald Trump later this year.