For years the United States official myth was that the US was an “honest mediator” in the Iran-UK dispute over the Iranian oil industry; that the US had only humanitarian and idealistic interests in its involvements in Iran. However, from early 1940s when Iran was invaded by the Allied forces as a supply route during WWII, the US had been developing other interests in Iran:
Unfortunately, Iran’s position geographically, bordering Russia on the north, with British oil interests in the south and its important strategic location in any war, will continue to make this country an object of basic interest to the major powers. It must be borne in mind that in any future war control of any part of Iran will allow the bombing either of the Russian oil fields in the north or of the British oil fields in the south. In the post-war period Iran’s location is of importance in connection with transit-landing facilities for the various world airway projects. It is these inescapable factors that give Iran an international importance and one beyond what its size and population would otherwise warrant.
It is, therefore, not for any sentimental reasons nor even for any idealistic democratic principles, worthy as these may be, that the United States is forced to take a continuing interest in Iran. [Colonel Harold B. Haskins, 1945, quoted in Badiozamani, Badi, East-West Understanding Press, NY, (2005), pp 50-51]
Indeed, the US had no interest in standing by while Iran nationalized its oil industry. Another common myth is that Truman’s administration was friendly towards Mossadeq’s government and Iranian aspirations, and it was the Eisenhower administration that changed that policy and supported the coup. But Truman was aware of the importance of the oil nationalization movement in Iran not only in terms of the Iran-Britain relations but in the larger picture in relation to other oil producing countries:
The President [Truman] said he thought Mexico’s nationalization of oil was ‘right’, even thought so at the time; but it was regarded as ‘treason’ to say so. If, however, the Iranians carry out their plans as stated, Venezuela and other countries on whose supply we depend will follow suit. That is the great danger in the Iranian controversy with the British. [Arthur Krock’s memories, quoted in Badiozamani, p 34]