With Cuba's proximity to the United States, Castro and his regime became an important Cold War ally for the Soviets. The relationship was for the most part economic, with the Soviet Union providing military, economic, and political assistance to Cuba. In 1972, Cuba gained membership into the Council of Mutual Economic Assistance (CMEA), which enhanced strong co-operation in the realm of national economic planning and increasingly gave Moscow economic control over Cuba. From 1976 to 1980, the Soviets invested US$1.7 billion on the construction and remodeling of Cuban factories and industry. Between 1981 and 1984 Cuba also received approximately US$750 million a year in Soviet military assistance.