Why did the US install the Shah of Iran?

The United States was not involved in the British-Soviet operation to force the resignation of Reza Pahlavi for his son in 1941. The United States was involved in the coup d'├ętat used to restore Mohammed Reza Pahlavi to the Imperial Throne in 1953. They did this at the whim of the British who desired the petroleum rights that were being denied them by the Mossadegh Regime. This act is seen by most Iranians to have been a cruel denial of their right to self-determination and nationalization of their own territorial resources.