Russia's military has been ordered to pull out of the Ukrainian city of Kherson, the only regional capital it captured after launching the so-called “special military operation” in Ukraine on February 24.
Russia's commander in Ukraine, General Sergei Surovikin, said it was no longer possible to keep supplying the city.
The withdrawal means Russian forces will pull out entirely from the western bank of the Dnepr River.
Western media reports say it is a significant blow as Russia faces a Ukrainian counter-offensive.
The military's top brass announced the decision on Russian state TV, with General Surovikin reporting on the situation on the ground in Kherson.
"In these circumstances, the most sensible option is to organize the defense along a barrier line along the Dnepr River," General Surovikin told the meeting.
The BBC says that after Russia's announcement, civilians inside Kherson said Chechen troops from the Russian military are in the city, in cafes, and moving around the streets.
Another civilian said: "Visually, nothing has changed. On the right bank [western bank] in Kherson, they are almost invisible, and it has been [like that] for several days. They have already taken everything they could. "There are a lot of them on the left bank, and they are building fortifications along the Dnipro and Plavni," he told the BBC.
Another Kherson resident, Olga, told the BBC there were fewer soldiers in the city.
Allies of President Putin – both who have been critical of Russia's war effort – reportedly welcomed the withdrawal.
Yevgeny Prigozhin, founder of the Wagner mercenary group and a long-time Putin associate, said that while the decision is “not a victorious step” it was important "not to agonize, not to get paranoidal, but to draw conclusions and work on mistakes".
Chechen leader Ramzan Kadyrov said General Surovikin had acted "like a real military general, not afraid of criticism."
NATO Secretary-General Jens Stoltenberg said it was "encouraging" to see Ukraine making advances.
Russian troops swept across southern Ukraine from annexed Crimea at the start of the war, seizing Kherson city in early March.
The withdrawal was reportedly announced shortly after Russian media said the deputy leader of Kherson, Kirill Stremousov, had been killed in a car crash.
Before the withdrawal, Russia moved thousands of civilians out of the city by boat, in what Ukraine condemned as a forced deportation.
General Surovikin was appointed to take over the running of Russia's invasion a month ago.