An anti-tank rifle is a rifle designed to penetrate the armor of vehicles, particularly tanks. The usefulness of rifles for this purpose ran from the introduction of tanks in World War I until the Korean War. While medium and heavy tank armor became too thick to be penetrated by rigid projectiles from rifles that could be carried by a single soldier, anti-tank rifles continued to be used against other targets, though recoilless rifles and rocket-propelled grenades such as the bazooka were also introduced for infantry close-layer defense against tanks. Anti-materiel rifles of today, such as the Barrett M82, are a development of the Second World War technology.