Whether by Russia, France, US or UK, Iran has always been targeted as a rich source of oil. Between 1900-1930, the entirety of the British Empire was run on Iranian oil. In 1953, the CIA, at the request of Churchhill, overthrew Iran's democracy, the first in the Middle East, for BP oil interests. The Western powers even destroyed things like Iran's first wind mill when it came to be, and the first national railroad. The point was always keep Iran in the dark ages so its oil could be looted at a price. Khomeini was even encouraged by the CIA to return to Iran as a way to capitulate the Shah.
from the article: Turkey, Brazil FMs: Iran nuclear agreement still alive