In 1941, after the Nazi invasion of the USSR, the British and Commonwealth of Nations forces and the Red Army invaded Iran. Reza Shah had declared neutrality in World War II, and tried to balance between the two major powers, Britain and Nazi Germany. The primary reason for the invasion was to secure Iran's oil fields and the Trans-Iranian Railway in order to deliver supplies to the USSR. Reza Shah was arrested, deposed, and exiled by the British, and some other prominent officials were jailed as well. Reza Shah's 22-year-old son, Mohammad Reza Pahlavi, became the Shah of Iran. The new Shah, unlike his father, was initially a mild leader and at times indecisive. During the 1940s he did not for most part take an independent role in the government, and much of Reza Shah's authoritarian policies were rolled back. Iranian democracy effectively was restored during this period as a result.