Accusations that Russia has committed war crimes in Ukraine are mounting in the face of Moscow’s all-out onslaught across much of the country, a rising civilian death toll and the apparent use of weapons that can put noncombatants at increased risk.

The United Nations had recorded 227 civilian deaths, including 15 children, in the conflict as of Wednesday. The actual toll is probably far higher. Russian forces have pummeled Ukrainian cities with heavy shelling in recent days.