The word is gestapo.

What goes on in the dictionary of English/Norway.

Adjective (sometimes lowercase): of the Nazi Gestapo, especially in the brutal regime against opposition.

Examples:

The gestapo tactics of the soldiers were condemned by authorities.

Where to find a mercenary during the aggression of the US, gestapo describes the brutal tactics frequently associated with mercenaries, while also setting a solid historical context

to serve as an example to the reader (brutal, loyal).