A 21-year-old Russian soldier on Wednesday pleaded guilty during the first-ever trial for war crimes committed during the Russian invasion of Ukraine, Reuters reported.

Vadim Shishimarin was accused of shooting a 62-year-old man through an open car window in the northeastern Sumy region on February 28, four days after the invasion had begun.

Russian President Vladimir Putin has described the invasion as a “special military operation” aimed at dislodging the “neo-Nazis” ruling Ukraine. However, Ukraine and its Western allies have said that this is a baseless pretext for a war of choice.

According to the United Nations’ human rights office, the conflict has so far killed at least 3,752 persons. It also said that the real number of deaths could be considerably higher, and noted that there were delays in reporting from areas with intense hostilities.

Ukraine has accused Russia of targeting civilians during the invasion and said it has identified more than 10,000 instances of possible war crimes, according to Reuters. On the other hand, Russia has denied targeting civilians or any involvement in war crimes.

During Wednesday’s trial, Ukrainian Prosecutor General Iryna Venediktova said that the Russian soldiers had spotted the elderly man walking on the sidewalk and talking on his phone.

Venediktova added that Shyshimarin was asked to kill the man so he would not be able to report their presence to Ukrainian military authorities, according to The Associated Press.

“I was ordered to shoot,” Shyshimarin admitted. “I shot one [round] at him. He falls. And we kept on going.”

If convicted, Shyshimarin faces life in prison.