Germany’s Cologne-Wahn military base has been sealed off after a suspected act of sabotage against its water supply, news outlets reported Wednesday.

The base near Cologne-Bonn airport employs 4,300 soldiers and 1,200 civilians and is also home to a fleet of military aircraft used by Chancellor Olaf Scholz for international travel.

According to news magazine Der Spiegel, authorities told employees at the base not to drink the tap water, as they believed it had been contiminated. They also found damage to a fence at the edge of the property.

Police, military police, and the military intelligence agency MAD are all looking into the alleged crime, Spiegel said.