The Chetniks […] were fighting the partisans often with more vigor than the Axis. They also would negotiate ceasefires with the Italians. They also at times made alliances with the Ustaše and Nazis against the partisans, and at times in alliance with the partisans against the [F]ascists.
Hold on, weren’t Cetniks the ones that were Nazi collaborators?
Yes and no:
(Source.)
Thank you