KYIV, UKRAINE -- An appeals court in Kyiv on Friday reduced to 15 years the life sentence of a Russian soldier convicted in the first war crimes trial since Russia invaded Ukraine in February.

The trial has been closely watched as an early test of whether it's possible to conduct fair trials during the ongoing conflict and of how well Ukraine's beleaguered justice system will stand up to the enormous task of prosecuting thousands of complex war crimes cases.

Critics said the sentencing of Vadim Shishimarin, a 21-year-old contract soldier who pleaded guilty to killing a civilian and was convicted in May, was unduly harsh, given that he confessed to the crime, said he was following orders and expressed remorse.

His defence lawyer, Viktor Ovsyannikov, had appealed to the court to reduce the sentence to 10 years. He said it was highly likely Shishimarin would be returned to Russia in a prisoner exchange.