Russia said its troops began pulling out of a strategic Ukrainian city on Thursday amid growing signs it was following through on a retreat that would mark a turning point in the grinding war.

Ukrainian officials acknowledged Moscow’s forces had no choice but to flee Kherson but remained cautious, fearing an ambush. It was difficult to know what was happening in the industrial port city, from which tens of thousands have fled in recent weeks and where remaining residents are frightened to leave their homes.

A forced pullout from Kherson — the only provincial capital Moscow has captured — would mark one of Russia’s worst setbacks yet, recalling its retreat from Kyiv in the early days of the war. Recapturing Kherson could allow Ukraine to win back lost territory in the south, including Crimea, which Moscow illegally seized in 2014.

A Russian retreat is also almost certain to raise domestic pressure on the Kremlin to escalate the conflict — which U.S. assessments showed may have already left tens of thousands of civilians and hundreds of thousands of soldiers dead or wounded.

The Russian Defense Ministry reported Thursday a “maneuver of units of the Russian group” to the opposite side of the Dnieper River from where Kherson lies — a day after the minister ordered a troop withdrawal from the city and nearby areas during a choreographed briefing by his top general carried on state TV.

Some Western observers, including the highest-ranking U.S. military officer, said they believed the Kremlin’s forces have been forced to pull out — though a full withdrawal could take some time.

And on Thursday, Ukrainian officials appeared to soften their skepticism somewhat. The armed forces commander-in-chief, Valeriy Zaluzhny, said that “the enemy had no other choice but to resort to fleeing,” since Kyiv’s army has destroyed supply systems and disrupted Russia’s military command in the area.

Zaluzhny also noted recent Ukrainian advances over the past month, saying that Kyiv’s forces have retaken 41 settlements in the Kherson region — which the Kremlin illegally annexed in September. That included 12 just on Wednesday.

Still, he said that Ukrainian military could not confirm or deny that Russian forces were indeed withdrawing.

Ukrainian presidential adviser Mykhailo Podolyak, meanwhile, warned that Russian forces had laid mines throughout Kherson, saying they wanted to turn it into a “city of death.”

Alexander Khara, of the Kyiv-based think tank Center for Defense Strategies, echoed those concerns, saying that he remains fearful of the possibility that Russian forces could destroy a dam upriver from Kherson and flood approaches to the city. The former Ukrainian diplomat also expressed fears about booby traps and possible other dangers left behind by the retreating Russians.

“I would be surprised if the Russians had not set up something, some surprises for Ukraine,” Khara said.

Residents said that Kherson was completely deserted Thursday and that explosions could occasionally be heard from the area of the Antonivskyi Bridge — a key crossing point on the Dnieper River that has been repeatedly targeted by Ukrainian bombardment.

“Life in the city seems to have stopped, everyone has disappeared somewhere and no one knows what will happen next,” said Konstantin, who insisted that his last name to be withheld for security reasons.

Russian flags have disappeared from the city’s administrative buildings, and there is no sign of the Russian military personnel who earlier moved into the apartments of evacuated residents, he said.

Ukrainian officials have been cautious throughout the war in declaring any victories against a Russian force that at least initially outgunned and outmanned them.

NATO Secretary General Jens Stoltenberg and British Prime Minister Rishi Sunak were careful in their assessments. Sunak spoke Thursday to Ukrainian president Volodymyr Zelenskyy, and his office said both men agreed “it was right to continue to exercise caution until the Ukrainian flag was raised over the city.”

Still, Army Gen. Mark Milley, chairman of the U.S. Joint Chiefs of Staff, said a day earlier that he believed a retreat was underway, but that Russia had amassed 20,000 to 30,000 troops in Kherson and a full withdrawal could take several weeks.

One analyst noted that the Ukrainian army has been systematically destroying bridges and roads for several months, making a quick transfer of Russian troops from one side of the river to the other an impossibility.

“The main question is whether the Ukrainians will give the Russians the opportunity to calmly withdraw, or fire at them during the crossing to the left bank,” Ukrainian military analyst Oleh Zhdanov said. “The personnel can be taken out on boats, but the equipment needs to be taken out only on barges and pontoons, and this is very easily shelled by the Ukrainian army.”

In other developments:

— An Indonesian government official said Thursday that Russian President Vladimir Putin would not attend the Group of 20 summit in Indonesia next week, avoiding a possible confrontation with the United States and its allies over his war in Ukraine.

— The head of Ukraine’s eastern Donetsk region, Pavlo Kyrylenko, said Thursday that three civilians had been killed in the region and another 12 wounded in the last 24 hours. Writing on Telegram, the official also reported that law enforcement officers had found the bodies of five people killed during the Russian occupation of the town of Yarova, which was retaken by Ukraine on September 19.

— Russian forces overnight pounded the city of Nikopol and nearby areas, Dnipropetrovsk Gov. Valentyn Reznichenko said. The shelling wounded a 80-year-old woman and damaged 10 residential buildings, a gas station, a gas pipeline and a power line. The neighboring Zaporizhzhia region was also shelled on Thursday morning, according to deputy head of Ukraine’s presidential office Kyrylo Tymoshenko.