A Return to Mass: Russian Force Expansion in the War with Ukraine

Key Points:

• Russia significantly expanded its military forces during the Russo-Ukrainian War, growing from a relatively small peacetime army to over 700,000 deployed personnel by 2024 through partial mobilization and large-scale contract soldier recruitment.
• Despite this quantitative growth, Russia failed to convert its manpower advantage into decisive battlefield breakthroughs due to Ukrainian tactical adaptations, technological innovations (notably drones), and Western support, which neutralized traditional Russian mass advantages.
• The Russian military's initial invasion force was ill-suited for a large-scale occupation and lacked adequate reserves, leading to heavy casualties and a scramble for replacements through mobilization, private military companies, and regional militias, resulting in a patchwork of low-morale units.
• By 2024 and 2025, Russian forces increasingly relied on small-unit infiltration tactics and light motorized assaults to cope with pervasive Ukrainian drone surveillance and prepared defenses, but these methods yielded slow, costly advances and diminishing operational returns.
• The war has prompted Russia to shift toward a larger, more mobilization-dependent force structure with expanded precision strike and drone capabilities near NATO borders, posing future strategic challenges, while NATO must adapt its defenses and tactics to counter Russia’s evolving military posture and innovations.