Through the Cold War, the United States, Soviet Union and other countries contemplated the possibility of nuclear warfare. While previous technology had developed to protect the crews of armored vehicles from projectiles and from explosive damage, now the possibility of radiation arose. In the NATO countries little if any development took place on defining a doctrine of how to use armed forces without the use of tactical nuclear weapons. In the Soviet sphere of influence the legacy doctrine of operational maneuver was being theoretically examined to understand how a tank-led force could be used even with the threat of limited use of nuclear weapons on prospective European battlefields. The Warsaw Pact arrived at the solution of maneuver warfare while massively increasing the number of anti-tank weapons. To achieve this, Soviet military theorists such as Vasily Sokolovsky (1897–1968) realized that anti-tank weapons had to assume an offensive role rather than the traditionally defensive role of the Great Patriotic War (1941–1945) by becoming more mobile. This led to the development of improved guided anti-tank missiles, though similar design work was being performed in Western Europe and the United States.