On the other hand, Russia faces its own domestic challenges: Sanctions are damaging its economy, and the industrial sector — which cannot easily import parts — is struggling to make enough precision weapons, Julian said.

Russia is also running low on troops who are available to fight. Putin could increase these numbers by instituting a draft. But doing so would require him to acknowledge that the war in Ukraine is, in fact, a war rather than the modest operation he has portrayed it as — probably because he knows public support is soft.

“As it stands, Russian options are shrinking,” Michael Kofman of CNA, a Washington research group, wrote recently. “The more they drag their feet, the further their ability to sustain the war deteriorates, and the worse their subsequent options.”