Walking through Bucha, a reporter encountered two dozen witnesses of the Russian occupation. Almost everyone said they saw a body, sometimes several more. Civilians were killed, mostly men, sometimes picked off at random. Many, including the elderly, say they themselves were threatened…

“It certainly appears to be very, very deliberate. But it’s difficult to know what more motivation was behind this,” a senior U.S. defense official said this week, speaking on condition of anonymity to discuss the military assessment.

The residents of Bucha, as they venture out of cold homes and basements, offer theories. Some believe the Russians weren’t ready for an extended fight or had especially undisciplined fighters among them. Some believe the house-to-house targeting of younger men was a hunt for those who had fought the Russians in recent years in separatist-held eastern Ukraine and had been given shelter in the town.

Sometimes, they say, the Russians themselves explained why they killed.