KYIV (Reuters) -- Russian Defense Minister Sergei Shoigu ordered his troops to withdraw from the west bank of the Dnieper River near the strategic southern Ukrainian city of Kherson in a significant setback for Moscow and potential turning point in the war.
Ukraine reacted with caution to Wednesday's announcement, saying some Russian forces were still in Kherson and additional Russian manpower was being sent to the region.
"They are moving out but not as much as would be taking place if it was a full pullout or regrouping," Oleksiy Arestovych, adviser to President Volodymyr Zelenskyy, said in a video posted online on Wednesday night.
Russian forces were destroying bridges as they left and mining roads, Arestovych said.
"And for the moment, we don't know their intentions -- will they engage in fighting with us and will they try to hold the city of Kherson? They are moving very slowly," he said.
Kherson was the only regional capital Russia captured after its invasion in February, and it has been the focus of a Ukrainian counter-offensive. The city controls both the only land route to the Crimean Peninsula that Russia annexed in 2014, and the mouth of the Dnieper, the river that bisects Ukraine. Russian-installed officials have been evacuating tens of thousands of civilians in recent weeks.
The Kherson region is one of four that President Vladimir Putin declared in September he was incorporating into Russia "forever," and which Moscow said had been placed under its nuclear umbrella.
In televised comments, Russian General Sergei Surovikin, in overall command of the war, reported to Shoigu that it was no longer possible to supply the city of Kherson. He said he proposed to take up defensive lines on the eastern bank of the Dnieper River.
Shoigu told Surovikin: "I agree with your conclusions and proposals. For us, the life and health of Russian servicemen are always a priority. We must also take into account the threats to the civilian population.
"Proceed with the withdrawal of troops and take all measures to ensure the safe transfer of personnel, weapons and equipment across the Dnieper River."
Ukrainian forces were strengthening their positions "step by step" in the south, Zelenskyy said in a Wednesday night address.
"There is a lot of joy in the information space today, and it is clear why, but ... the enemy will make no gifts to us," said Zelenskyy, mentioning Kherson just once in his five-minute speech.
U.S. President Joe Biden said Moscow's order to withdraw from Kherson was "evidence of the fact that they have some real problems with the Russian military."
Biden said he hopes Democrats and Republicans can continue the bipartisan approach of confronting Russia's aggression in Ukraine after Tuesday's midterm elections, in which his Democratic Party performed better than expected.
A regular evening statement by the Ukrainian military on Wednesday made no direct reference to the Kherson region or its capital. Russian forces shelled more than 25 towns and villages on the southern front along the line of contact, it said, and there were more than 50 drone reconnaissance missions.
Ukrainian legislator David Arakhamia, who led Kyiv's delegation to peace talks early in Russia's invasion, said however, that a military operation in the Kherson region was underway.
He described the Russians' situation as critical and said, "Sooner or later, they will either leave Kherson, Donetsk, Luhansk and Sevastopol [in Crimea] or be destroyed."
If Ukrainian forces take the entire west bank of the Dnieper, their U.S.-supplied long-range artillery and HIMARS multiple rocket launchers would be able to strike Russian logistics bases and positions on the east bank, according to military experts.
But the Ukrainians may face numerous booby traps and could be targeted by intense Russian artillery barrages.
NATO Secretary Gen. Jens Stoltenberg, on a visit to London, welcomed the news from Kherson but also struck a note of caution.
"We should not underestimate Russia. ... We have seen the drones, we have seen the missile attacks. It shows that Russia can still inflict a lot of damage," he told Sky News.
Compounding the sense of Russian disarray in Kherson, Moscow's number two official there, Kirill Stremousov, was killed on Wednesday in what Moscow said was a car crash.
Russia's leading war hawks on Wednesday swiftly voiced support for the decision to abandon the city of Kherson, putting a brave face on one of Moscow's most humiliating retreats in nearly nine months of war.
"After weighing all the pros and cons, Gen. Surovikin made the difficult but right choice between senseless sacrifices for the sake of loud statements and saving the priceless lives of soldiers," said Ramzan Kadyrov, the Chechen leader who has frequently urged a more aggressive approach to the war.
Earlier on Wednesday, the main bridge on a road out of Kherson was blown up.
Photos on the internet showed the span of the Darivka bridge on the main highway east out of Kherson completely collapsed into the Inhulets River, a tributary of the Dnieper. Reuters verified the location of the images.