CNN reports: South Korean President Moon Jae-in said it was "a sleepless night" for him ahead of meeting between US President Trump and Kim Jong Un on Tuesday.
Speaking ahead of a cabinet meeting, Moon said he hoped the summit would be a success so a "new chapter" could open.
"The NK-US summit has just begun and I believed all Koreans have their eyes fixed on Singapore," he said.
Moon is seen by many as the architect of the breakthrough in diplomacy with North Korea. Elected in 2016, he has long been an advocate of peaceful relations with Pyongyang.