Russia's defense ministry said on Friday it had completed the withdrawal of troops from the western bank of the Dnipro river in Ukraine's southern Kherson region.
In its daily briefing, the ministry said all Russian forces and equipment had been transferred to the left, or eastern, bank of the Dnipro. It said the withdrawal was completed by 5:00 a.m. Moscow time on Friday morning.
Russia ordered the withdrawal on Wednesday after it said it attempts to maintain its position and supply troops were "futile" in the face of a mounting Ukrainian counteroffensive.
"The transfer of Russian troop units to the left bank of the Dnipro river has been completed," the defense ministry said in a statement.
"Not a single unit of military equipment or weapons have been left on the right (western) bank. All Russian servicemen crossed to the left bank," it added, saying that Russia had not suffered any loss of personnel or equipment during the withdrawal.
Reuters could not independently verify those details. Pro-Russian war bloggers had reported late on Thursday that Russian forces crossing the river were coming under heavy fire from Ukrainian forces. The ministry said Ukrainian forces had struck Dnipro River crossings five times overnight with US-supplied HIMARS rocket systems.
The withdrawal marks one of Russia's biggest retreats in its nine-month war, after failing in an initial advance on the capital Kyiv and being ousted from the northeastern Kharkiv region in early September.
The Russian defense ministry said it had adopted "defensive lines and positions" on the eastern bank of the river, which Moscow hopes it will be able to better supply and defend.
Kherson is still 'part of Russia'
The Kremlin said on Friday that Russian forces' withdrawal from Kherson would not change the status of the region, which Moscow has proclaimed part of Russia after moving to annex it from Ukraine.
Russia claimed Kherson and three other Ukrainian regions after holding what it called referendums in September – votes that were denounced by Kyiv and Western governments as illegal and coercive.
In a conference call with reporters, Kremlin spokesman Dmitry Peskov said the region's status was "defined and fixed" and that no changes were possible.
Russian strike on Mykolaiv
Six people were killed in a Russian missile attack on an apartment building in the southern Ukrainian city of Mykolaiv early on Friday, Mayor Oleksandr Senkevych said.
Rescuers were digging through the debris for survivors, Senkevych wrote on the Telegram messaging app.
A Reuters reporter in the area heard three impacts, the first at around 3:00 a.m.
Photographs posted by Senkevych showed a gaping hole in the multi-story building and emergency workers combing through a mound of rubble.
Ukrainian forces are steadily advancing further south towards the nearby city of Kherson, from which Russia has said its forces are withdrawing after occupying it since March.
Officials in Kyiv say their troops have reclaimed dozens of settlements in the area.
In an interview with Reuters on Thursday, Ukrainian Defence Minister Oleksii Reznikov said it would take at least a week for Russian troops to leave Kherson.