Swiss media say Johan Cosar is accused of training and fighting with the Syriac Military Council militia from 2013 to 2015. Cosar's military trial on charges of joining a foreign army and recruiting other Swiss citizens opened Wednesday.
Court spokesman Mario Camelin said a concern for Swiss authorities was that a veteran of the armed forces fighting for a foreign militia could jeopardize the Alpine country's long-vaunted neutrality. If convicted, Cosar could be fined and sentenced to up to three years in prison.
Camelin said Cosar's cousin also is on trial.