BLAHODATNE, Ukraine — Ukraine’s troops swept into the key southern city of Kherson on Friday, its military said, greeted by jubilant residents waving Ukrainian flags after a major Russian retreat.
The move puts Kyiv on the cusp of achieving one of its most significant victories of the war and deals a bitter blow to President Vladimir V. Putin, who just a month ago declared the Kherson region a part of Russia forever.
“Today is a historic day,” the Ukrainian president, Volodymyr Zelensky, said in a message posted on the Telegram messaging app. “We are returning to Kherson. As of now, our defenders are on the approaches of the city. But special units are already in the city.”
Videos shared by Ukrainian government officials on social media showed scenes of civilians who had endured nearly nine months of occupation cheering the arrival of a contingent of Ukrainian troops.
Other videos showed cars driving in the city center beeping horns as people on the sidewalks shouted “Glory to Ukraine!” In one, Ukrainian soldiers drove slowly past a crowd as people reached out to touch the soldiers through the open windows.
Hours earlier, the Kremlin had issued a statement saying that the withdrawal of its forces across the Dnipro River was complete, though residents reported that there were still Russian soldiers in the city, some wearing civilian clothes.
“Kherson is returning under the control of Ukraine, units of the Armed Forces of Ukraine are entering the city,” the Ukrainian military intelligence agency said in a statement.
The military later warned that Russia was preparing to strike the city from new positions across the river. A major bridge connecting the city of Kherson to the eastern bank was blown up in a massive explosion early Friday, residents said.
The loss of Kherson would be Russia’s third major setback of the war, following retreats from Kyiv, the capital, last spring, and from the Kharkiv region in the northeast in September. Kherson was the only provincial capital Russia had captured since invading in February, and it was a major link in Russia’s effort to control the southern coastline along the Black Sea.
Recapturing control of Kherson would also bolster the Ukrainian government’s argument that it should press on militarily while it has Russian forces on the run, and not return to the bargaining table, as some American officials have advocated.
The few residents who remain in Kherson have endured curfews, shortages of goods, partisan warfare and an intense campaign to force them to become Russian citizens and accept Moscow’s warped version of their culture and history.
The depth of their suffering has yet to come into focus. For months, residents interviewed by journalists have told stories of friends being abducted, children illegally deported, relatives tortured and killed. Evidence of human rights abuses has surfaced when Russian have pulled out elsewhere.
The dramatic scenes in Kherson came less than 48 hours after Russia’s defense minister announced that Russian troops in the city would withdraw.
Even as its soldiers fled, the Kremlin said that it still considered Kherson — which President Vladimir V. Putin illegally annexed in September — to be a part of Russia.
“This is a Russian region,” Dmitri S. Peskov, the Kremlin’s spokesman, told reporters on Friday. “It has been legally fixed and defined. There can be no changes here.”
As he spoke, Ukrainian soldiers continued to move through towns and villages in the region.
Oleh Voitsehovsky, the commander of a Ukrainian drone reconnaissance unit, said he had seen no Russian troops or equipment in his zone along the front less than four miles north of Kherson city.
“The Russians left all the villages,” he said. “We looked at dozens of villages with our drones and didn’t see a single car. We don’t see how they are leaving. They retreat quietly, at night.”
Serhiy, a retiree living in Kherson who asked that his last name not be published for security reasons, said in a series of text messages that conditions in the city had unraveled overnight.
“At night, a building burned in the very center, but it was not possible even to call the fire department,” he wrote. “There was no phone signal, no electricity, no heating and no water.”
“I am waiting for our army,” he said.
Andrew Kramer, Anna Lukinova, Maria Varenikova and Ivan Nechepurenko contributed reporting.