Russia’s military made its largest territorial gains in more than two years in October, as it pressed farther into Ukraine’s eastern Donbas region — but at a heavy cost.

British and Ukrainian military officials, as well as BBC researchers, claim that Russia suffered its highest rate of dead and injured soldiers during that month. The arrival of thousands of North Korean troops in Russia is also raising questions about whether the Kremlin has enough soldiers to make up for its losses.
What do we really know about Russia’s casualties and its ability to replace them?

The losses that matter

It is difficult to obtain concrete information about Russian casualties, which comprise deaths and injuries. Moscow has an incentive to minimize its losses and rarely discloses any information; Ukraine and its allies have an incentive to overstate them.

Even if they are accurate, the Western casualty estimates usually lump together deaths with all injuries. Military experts say that category is too broad to fully explain the state of the war. Lightly wounded soldiers can quickly recover, for example.

What determines a military’s true ability to fight are its irreplaceable, irrecoverable or permanent losses — soldiers who are dead or so seriously injured that they will never see battle again.