Soviet military doctrine used snipers for providing long-distance suppressive fire and for eliminating targets of opportunity, especially leaders, because during World War II, Soviet military leaders and combat theorists (Vassili Zaitsev contributed greatly to Soviet sniper doctrine, although he was officially neither of these) found that military organisations have difficulty replacing experienced non-commissioned officers and field officers during times of war. They found that the more expensive and less rugged sniper rifles could match the cost-effectiveness of a cheaper assault rifle given good personnel selection, training, and adherence to doctrine. The Soviet Union used women for sniping duties, including Lyudmila Pavlichenko and Nina Lobkovskaya.