Russia's defence ministry said it has finished pulling out its troops from the western bank of the river dividing Ukraine's southern Kherson region – including the only provincial capital Moscow had captured since invading its neighbour.
In a statement carried out by Russian state news agencies, the ministry said the withdrawal was completed at 05:00 on Friday.
No military equipment was left behind, it said, but the retreat still marks another huge setback for Russia in its eight-and-a-half-month war in Ukraine.
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The Kremlin remained defiant today, insisting the development in no way represents an embarrassment for Russian President Vladimir Putin.
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Moscow continues to view the entire Kherson region as part of Russia, Kremlin spokesman Dmitry Peskov told reporters.
He said the Kremlin does not regret holding festivities just over a month ago to celebrate the illegal annexation of Kherson and three other occupied or partially occupied regions of Ukraine.
Shortly before the Russian announcement, the office of Ukrainian President Volodymyr Zelensky described the situation in the Kherson region as "difficult".
It reported Russian shelling of some of the villages and towns Ukrainian forces reclaimed in recent weeks during their counteroffensive in the Kherson region.
Ukrainian officials were wary of the Russian pullback announced this week, fearing their soldiers could get drawn into an ambush in Kherson city, which had a pre-war population of 280,000.
Military analysts had also predicted it would take Russia's military at least a week to complete the troop withdrawal.
Ukrainian presidential adviser Mykhailo Podolyak said on Thursday the retreating Russian troops laid mines throughout Kherson to turn it into a "city of death". He also predicted they would shell the city after relocating across the Dnieper River.
Having previously warned the Russian retreat might be a trap, some quarters of the Ukrainian government barely disguised their joy at the pace of the withdrawal.
"The Russian army leaves the battlefields in a triathlon mode: steeplechase, broad jumping, swimming," Andriy Yermak, a senior presidential adviser, tweeted.
Social media videos apparently filmed by soldiers on routes toward Kherson showed villagers hugging the Ukrainian troops.
Recapturing the city could provide Ukraine with a strong position from which to expand its southern counteroffensive to other Russian-occupied areas, potentially including Crimea, which Moscow seized in 2014.
From its forces' new positions on the eastern bank, however, the Kremlin could try to escalate the war, which US assessments showed may already have killed or wounded tens of thousands of civilians and hundreds of thousands of soldiers.
A Russian S-300 missile strike overnight killed six people in Mykolaiv, a city about 42 miles from Kherson's regional capital, Mr Zelensky's office said on Friday morning.
Rescue crews sifted through the rubble of a five-storey residential building in search of survivors.
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Mr Zelensky called the missile strike "the terrorist state's cynical response to our successes at the front".
"Russia does not give up its despicable tactics and we will not give up our struggle. The occupiers will be held to account for every crime against Ukraine and Ukrainians," Mr Zelensky said.
The president's office said Russian drones, rockets and heavy artillery strikes across eight regions killed at least 14 civilians between Thursday morning and Friday morning.
In the Dnipropetrovsk region, more than 50 rockets were fired overnight around cities and towns located across the Dnieper River from the Zaporizhzhia nuclear power plant, according to governor Valentyn Reznichenko.
The state of the key Antonivskiy Bridge linking the western and eastern banks of the Dnieper in the Kherson region remained unclear today and could be key to determining whether the Russians did in fact all leave Kherson city.
Russian media reports suggested the bridge was blown up following the Russian withdrawal; pro-Kremlin reporters posted footage of the bridge missing a large section. But Sergei Yeliseyev, a Russian-installed official in the Kherson region, told the Interfax news agency "the Antonivskiy Bridge hasn't been blown up, it's in the same condition".