Ukraine's armed forces have begun to pull back from the town of Stanytsia Luhanska in the Luhansk region, one of only six civilian crossing points along the 450-kilometer line of contact in the Donbas war zone.
In a Facebook post, Ukrainian Lieutenant General Oleksandr Syrsky, commander of the Joint Forces Operation in the Donbas, said soldiers left "one of their positions" at the checkpoint at noon.
A seven-day cease-fire preceded the withdrawal of troops, tweeted Varvara Pakhomenko, head of the Ukraine mission for humanitarian group Geneva Call.
"I witnessed [a] historic moment," she said while posting a picture of the crossing point.
The Organization for Security and Cooperation in Europe (OSCE), which monitors adherence to the Minsk truce between the Ukrainian military and Moscow-backed militants, welcomed the move.
Yasar Halit Cevik, the OSCE's chief monitor in Ukraine, expressed his team's "full readiness to monitor the disengagement process."
He said additional monitoring patrols had been dispatched to the area, which is located 15 kilometers northeast of the regional capital of Luhansk.
"The [OSCE] mission is also conducting remote observation with cameras and unmanned aerial vehicles," Cevik said.
The Russian-backed armed units in the area have also begun withdrawing from their positions and their representatives said it will take three days to complete.
Stanytsia Luhanska has been a flashpoint since April 2014, when the military conflict in eastern Ukraine started.
A bridge was blown up there in early 2015, rendering it only passable by foot.
In 2018, the United Nations earmarked funds to repair the bridge, but constant fighting has made infrastructural improvements impossible in the area.
It is just one of two crossing points in the Luhansk region.
The UN says that more than 13,000 people have been killed in the conflict, and 1.5 million more internally displaced -- the biggest displacement of people on the European continent since World War II.