North Korea has changed time zone to match the South after last week's inter-Korean summit, according to state media.
At 23:30 local time (15:00 GMT) on Friday the country's clocks moved forward 30 minutes to midnight.
The reset is "the first practical step" to speed up Korean unification, the official KCNA news agency said.
Meanwhile, US President Donald Trump says he has a date for his meeting with the North's leader, Kim Jong-Un.
"We now have a date and we have a location, we'll be announcing it soon," Mr Trump told US journalists outside the White House on Friday, adding that he was expecting "very, very good things" to come out of it.
Mr Trump will host South Korea's president Moon Jae-in at the White House on 22 May to discuss the upcoming meeting.
Until now, it was on Pyongyang Time, which is half an hour behind South Korea and Japan.
It introduced the extra 30 minutes in 2015 as a stand against "wicked Japanese imperialists", because its hours were changed to match Tokyo's when the Korean peninsula was under Japan's rule.
South Korea (which is nine hours ahead of GMT) had also moved away from Japanese time in the 1950s but it switched back again in the 1960s.
Two clocks – showing the time in North and South Korea – sit side by side in Panmunjom, the town in the so-called Demilitarized Zone (DMZ) where the two countries' leaders recently met.
After the talks, South Korea's presidency sent a tweet saying Mr Kim was distressed by seeing the clocks.
President Trump did not share details on the time and place for the landmark meeting with Mr Kim.
It is expected to happen in May or early June.
Mr Trump has previously expressed a preference for meeting in the demilitarized zone between the North and South but Singapore is also an option.
The meeting was suggested and provisionally agreed in March, after a South Korean delegation met Mr Kim in Pyongyang and later visited the White House.
America's main goal is to secure the North's nuclear disarmament.
Discussions are already believed to be underway to secure the release of three US hostages held in North Korea before the two leaders come face to face.