Putin used the same siege tactics in Syria and Chechnya, Blumenthal said. Russia, for example, bombed the Syrian city of Aleppo for weeks in 2016, likely killing hundreds of civilians, according to Human Rights Watch.

“He has no compunction about loss of life to achieve his really warped, cruel goals,” Blumenthal said. “In this case, his goal is to rebuild the empire that was the Soviet Union. A siege is likely and may last as long as several weeks. He’ll try to wear down resistance in Kyiv and Kharkiv and other major cities, hitting civilian centers with massive explosives, airstrikes and missiles.”

But even if Putin’s siege tactics allow the Russians to enter Kyiv, he doesn’t have the troops needed to secure it, said retired Gen. Peter Chiarelli, the former Army vice chief of staff. Putin has deployed more than 150,000 Russian troops to Ukraine’s borders, but not all of them are in the country.

A veteran of the Iraq insurgency, Chiarelli estimated as many as 15% of the population in Baghdad wanted to kill U.S. troops. Kyiv will be far different for Russian troops, who will face near-universal resistance.