A Czech citizen has been sentenced to 13 days of administrative detention after staging a protest on Moscow’s Red Square, according to the press service of the Tverskoy District Court.

The man, identified as Michal Plamenek, was detained on the afternoon of September 20 after holding a placard written in English near Lenin’s Mausoleum, the court said, The Caspian Post reports.

Authorities did not reveal the wording of the sign. However, the court said the judge determined that the inscription was aimed at “discrediting the Russian Armed Forces.”

Police detained Plamenek because Red Square is located next to the Kremlin, where public demonstrations are prohibited. He was also accused of refusing to accompany officers to a police station and resisting detention.

The court found him guilty of three administrative offenses: “discrediting” the Russian Armed Forces, violating rules governing public events, and failing to comply with a lawful police order.

Plamenek was fined 40,000 rubles ($470) for “discrediting” the military and another 20,000 rubles ($237) for violating protest regulations. He received the 13-day administrative detention sentence for disobeying police.