Occupation of Iran in World War 2

The British had two plans.  The first one involved a British-only operation, occupying just the oil fields.  The second one involved a joint attack, occupying all the military significant parts of Iran.  Therefore, the British sent the first in a series of notes demanding the removal of the Germans, although concerns over Turkish opinion withheld the really strong language for the time being.  The British also sought US backing, while we have no record of what Churchill and Roosevelt said to each other, clearly Churchill was left with the impression that the US gave the go-ahead, although the Iranians continued to seek US assistance and meditation.  Desperately, the Shah’s government (just how well-informed the Shah himself was is a matter of mystery) tried to buy time for the war’s outcome to be determined.