Russian irregular units in Ukraine

Over the course of the Russian invasion of Ukraine, which began in February 2022, irregular military units began to play a more prominent role in the fighting, alongside the regular Russian Armed Forces. In the face of waning recruitment levels for the military as casualties mounted, the Russian government increasingly turned to a variety of mercenaries, militias, paramilitaries, and mobilized convicts.

Source: Wikipedia — Russian irregular units in Ukraine (CC BY-SA 4.0)