Vladimir Putin speaks during an event. File

Russia's Feb.24 invasion of its southern neighbour has been halted on most fronts by stiff resistance from Ukrainian forces who have recaptured territory even as civilians are trapped in besieged cities.

"We have information that Putin felt misled by the Russian military," leading him to mistrust the military leadership, the US official said, speaking on condition of anonymity and citing newly declassified intelligence reports.

"Putin didn’t even know his military was using and losing conscripts in Ukraine, showing a clear breakdown in the flow of accurate information to the Russian president," the official said.

The official did not provide the intelligence report, but said the information had been declassified.

The Kremlin made no immediate comment after the end of the working day in Moscow, and the Russian embassy in Washington did not immediately reply to a request for comment.

Washington's decision to share its intelligence more publicly reflects a strategy it has pursued since before the war began. In this case, it could also complicate Putin's calculations, a second U.S. official said, adding, "It's potentially useful. Does it sow dissension in the ranks? It could make Putin reconsider whom he can trust."

One senior European diplomat said the US assessment was in line with European thinking. "Putin thought things were going better than they were. That's the problem with surrounding yourself with 'yes men' or only sitting with them at the end of a very long table," the diplomat said.

Russian conscripts were told they were taking part in military exercises, but had to sign a document before the invasion that extended their duties, two European diplomats said.

"They were misled, badly trained and then arrived to find old Ukrainian women who looked like their grandmothers yelling at them to go home," one of the diplomats added.

There were no indications at the moment that the situation could foster a revolt among the Russian military, but the situation was "unpredictable" and Western powers "would hope that unhappy people would speak up," the senior European diplomat said.

Military analysts say Russia has reframed its war goals in Ukraine in a way that may make it easier for Putin to claim a face-saving victory despite a woeful campaign in which his army has suffered humiliating setbacks.

Russian forces bombarded the capital Kyiv and northern Chernihiv on Wednesday, a day after Russia promised to scale down military operations in both cities.

"We believe that Putin is being misinformed by his advisers about how badly the Russian military is performing and how the Russian economy is being crippled by sanctions, because his senior advisers are too afraid to tell him the truth," the US official said.

Russia says it is carrying out a "special operation" to disarm and "denazify" its neighbor. Western countries say Moscow launched an unprovoked invasion.

Reuters