Final answer:
The Soviet Union and the United Kingdom invaded and occupied Iran during WWII to secure oil resources and establish a supply route for the Allies.
Step-by-step explanation:
During World War II, Iran was invaded and occupied by the Soviet Union and the United Kingdom. The Allied forces entered Iran in August 1941, aiming to use Iran as a transport route for supplies and to block potential German access to the valuable Iranian oil. Iran's strategic importance was recognized by the Allies, particularly after the Tehran Conference in 1943, where the leaders of the United States, the Soviet Union, and the United Kingdom convened to discuss the next steps in the war. The Iranian occupation ended in 1946, after the cohesive efforts of the Allies during the war. Despite the occupation, Iran played a crucial role as a supply route for the Soviet Union and contributed to the Allied victory.