Anti-government anarchists are expected to gather in Heidelberg and Kaiserslautern, Germany, this week in a revival of the so-called Chaos Days protests of the 1990s, according to a U.S. Army Europe advisory.

German authorities recently learned of the protests though various social media. Military officials are urging U.S. personnel to take precautions and to avoid demonstration sites.

In Kaiserslautern, a protest is possible at the main train station Monday between 1 p.m. and midnight. It is unknown where the protesters, known as “punkers,” will march or how many are expected to participate. German police are investigating and will ensure sufficient forces are in place to quell any violence, according to USAREUR. In Heidelberg, protesters have called for a “warm-up to Chaos Day” at the Bismarckplatz on Monday, possibly continuing through Wednesday.

The purpose of the protests is to show dissatisfaction with the government and authority in general, according to authorities. Typical activities involve public drunkenness and disorderly conduct such as spray painting and smashing windows.