Why was this Russian case tried in a military court?

Russia tried left-wing activists in a military court, as reported here in The New York Times. The defendants claim they were tortured. But why was the case tried in a military court?

Human rights jurisprudence strongly disfavors the trial of civilians in military courts. Among the countries that routinely violate this rule: Uganda, Cameroon, Lebanon, Egypt, and Pakistan (until recently). Russia needs to kick this nasty habit.