In handing down her verdict and sentence on September 9, the judge said she was giving Stanic the minimum penalty for the offense of participating in a war or armed conflict in a foreign country, if the offense was committed as part of a group.

Stanic was arrested in July 2022 at Belgrade's Nikola Tesla airport and admitted he had join pro-Russian forces in eastern Ukraine as part of the Hussar Regiment paramilitary formation.

Katarina Ninkovic, Stanic's lawyer, told RFE/RL after the court made its ruling that her client will file an appeal.

"We believe that there is no real crime here because, at the time the crime was committed, my client did not even know that it was prescribed as a criminal offense. This crime of participation in war or armed conflict is prescribed in our legislation in 2014. He committed the crime in 2015, six months after we introduced it in the first place," Ninkovic said.

Stanic helped man a checkpoint in the eastern Ukrainian town of Snezno, which was under the control of pro-Russian forces.