Occupation of Iran in World War 2

Stubbornly, the Shah refused to compromise with Russia, despite the Iranian military realising that a defence of the soviet target areas was impossible.  However, Stalin reduced pressure in August, apparently out of the concern that the British might attack the soviet oil wells if he invaded.  The successful defence of British airspace in the battle of Britain also impressed Stalin, although the rumblings of a German attack on Russia may also have deterred him.