Germany’s Cologne-Wahn military base was sealed off for several hours on Wednesday due to a suspected sabotage of its water supply.

A guard discovered a hole in the fence near the base’s water processing plant, prompting an investigation and a ban on drinking tap water until safety could be confirmed.

Military and police authorities are investigating the incident, which has raised security concerns.

In response, security at a nearby NATO air base in Geilenkirchen was heightened, though no issues were found there, the DW has reported.

The incident is part of a broader pattern of increasing Russian intelligence activities against NATO member states.

Written by B.C. Begley