Ukrainian and separatist rebel officials say both sides have begun pulling back forces and equipment from a frontline area of the conflict that has killed more than 13,000 people in the past five years.
The Saturday pullback in the Petrivske area follows two similar movements in eastern Ukraine, where Russia-backed rebels and Ukrainian forces have been fighting since 2014. The withdrawals are seen as a significant step that could lead to a summit of Russia, Ukraine, France and Germany on ending the conflict.
The Petrivske withdrawal initially was set for last weekend, but Ukraine called that off because of what it said were cease-fire violations by the rebels.
Ukraine military spokesman Andrei Andreev and the rebel news agency DAN confirmed both sides began moving at midday.
The full pullback, with each side moving to one kilometer (0.6 miles) away from the front line, is expected to take three days, after which demining of the area is to take place.
Along with the rebel and military moves, tensions have also shown signs of easing after Ukraine and Russia each exchanged 35 prisoners to the other side in September.
But final resolution of the conflict remains elusive and argument continues over when and how elections could be held in the rebel territories that would allow them to achieve special status within Ukraine.