Russian leadership was deluded that Ukraine would collapse at the first sign of fighting, and that President Volodymyr Zelensky would flee, said Nick Reynolds, a military analyst at the Royal United Services Institute.

“That was a catastrophic failure to understand Ukrainian society and the Ukrainian state,” Mr. Reynolds said.

Even outnumbering Ukrainian fighters by 10 to one might not be enough to take the city, given Russia’s inability to coordinate its ground forces with intelligence, air power and engineering, some analysts said.

“You need to be good at this,” said Scott Boston, an analyst at RAND who studies the Russian military and land warfare. “And I don’t think I have any real evidence that Russia has trained to do large-scale urban warfare.”