A Ukrainian court has sentenced a 21-year-old Russian soldier to life in prison for killing a Ukrainian civilian.

It is the first conviction for war crimes since Russia’s invasion three months ago.

The soldier had pleaded guilty and testified that he shot the man after being ordered to do so. The sentencing came as the United Nations said the 3-month-old war has helped push the number of people displaced worldwide to the highest level on record level.

More 100 million people have been driven from their homes across the globe. Grinding battles in the Donbas, where Ukrainian and Russian forces are fighting town by town, have forced many civilians to flee their homes.