Russia’s defence minister announced on television on Wednesday that he was ordering the retreat of Moscow’s forces from the strategically important southern city of Kherson, in a potentially serious blow to President Vladimir V. Putin’s war effort.

The move came after General Sergei Surovikin, the commander of Russia’s forces in Ukraine, told Sergei K. Shoigu, Russia’s defence minister, that the decision was “difficult” but that a withdrawal would “preserve lives of servicemen and combat readiness of forces”.

The Ukrainian military had warned that Russian forces might try to feign a retreat in hopes of drawing them into urban combat. The military had till Wednesday been tracking signs of a Russian retreat but was not convinced the Russian military intends to fully withdraw from Kherson City and the surrounding Russian bridgehead on the western bank of the Dnipro river, Roman Kostenko, a colonel in the army and chairman of the defence and intelligence committee in Ukraine’s parliament, said in a telephone interview. “We have signs they are pulling out,” Colonel Kostenko said.

“They blew up bridges that would have allowed our forces to advance. We see them leaving population centres, but in some, they leave soldiers behind to cover their movements.” Ukrainian intelligence agencies were working to assess Russia’s movements, he said and noted that the announcement could be misdirection from the Russian military.

“We understand it is Russia” making the announcement, he said. “We are watching.” Deep anxiety about the announced withdrawal coursed through the reports from influential Russian military bloggers throughout Wednesday, with many seeing it as a betrayal.

“The decision is shocking to thousands and millions of people who are fighting for Russia, dying for Russia, believe in Russia and share the beliefs of the Russian world,” wrote Yuri Kotyonok, an influential blogger. A retreat from the city of Kherson would be a major victory for Ukrainian forces, who have long sought to recapture it and push back Russian troops from the western bank of the Dnipro river. It is the only regional capital under Moscow’s control, and the withdrawal would also be a humiliating public rout for Putin, who western intelligence officials said, had rejected earlier requests from commanders that they be allowed to pull back from the city.

The Russian-appointed civilian administration had already fled to new headquarters east of the Dnipro, and residents have reported widespread looting by Russian forces. The residents of Kherson have been without power for four days, and communications have been severed. A Russian retreat from Kherson would have both strategic and symbolic importance. The vital Black Sea port was the first major city to fall to Russian control less than a week after the invasion. Kherson, a shipbuilding city about340 miles from Ukraine’s capital, is an important node for access to the Black Sea and a gateway to Crimea. It also provides access to Ukraine’s southern coastline.