During World War II, as German armies achieved success against the Soviet Union, the Iranian government, anticipating a German victory, refused British and Soviet demands to expel German residents. This led to the Allied invasion of Iran in August 1941 under Operation Countenance, where they easily overpowered Iran's weak army. The primary objectives were to secure Iranian oil fields and establish the Persian Corridor, a supply route to the Soviet Union. Despite the invasion and occupation, Iran maintained an official stance of neutrality. Reza Shah was deposed during this occupation and replaced by his son, Mohammad Reza Pahlavi.^[82]

The Tehran Conference in 1943, attended by the Allied powers, resulted in the Tehran Declaration, assuring Iran's post-war independence and territorial integrity. However, post-war, Soviet troops stationed in northwestern Iran did not promptly withdraw. Instead, they supported revolts leading to the establishment of short-lived, pro-Soviet separatist states in Azerbaijan and Iranian Kurdistan - the Azerbaijan People's Government and the Republic of Kurdistan, respectively, in late 1945. The Soviet presence in Iran continued until May 1946, ending only after Iran promised oil concessions. However, the Soviet-backed republics were soon overthrown, and the oil concessions were subsequently revoked.^[83]