Primary Russian forces consisted of two organized units known as ""РДО-1"" and ""РДО-2"" (РДО stands for "Русский Добровольческий Отряд", which means "Russian Volunteer Unit"), commanded by Yuriy Belyayev and Alexander Zagrebov, respectively. "РДО-2" was also known as "Tsarist Wolves", because of the monarchist views of its fighters. Another unit of Russian volunteers was composed of hundreds of cossacks, known as the ""First Cossack Sotnia"". All these units were operating mainly in Eastern Bosnia along with VRS forces from 1992 up to 1995.