Battle-hardened separatists led by former Ukrainian special forces commanders are fighting for Russia and spearheading the assault on Mariupol.
Ukrainian-born soldiers fighting for the breakaway states of Donetsk and Luhansk, the self-proclaimed people’s republics, are among the most experienced combatants on either side of the conflict.
An estimated 34,000 are thought to be fighting for the United Armed Forces of Novorossiya, the name given to the loose conglomeration of professional units and militia groups that formed in the aftermath of the 2014 revolution when the two republics broke away from Ukraine. Novorossiya is a Tsarist colonial term for areas of eastern Ukraine.
Some of their equipment lags behind that used by regular Russian troops
ALEXANDER ERMOCHENKO / REUTERS
Russian-backed separatist forces are nominally in charge of the operation to capture Mariupol, having first attempted to take the port city