Final answer:
The concessions to Britain and Russia resulted in foreign occupation, political interventions, and a coup that installed a pro-Western Shah in Iran, undermining nationalist movements and leading to long-term political instability and resentment, ultimately contributing to the Islamic Revolution.
Step-by-step explanation:
The effect of the concessions granted to Britain and Russia in Iran had significant implications for the country's sovereignty and political landscape. When Iran became a strategic concern during and after World War II, the Allies' occupation and subsequent political interferences paved the way for a tumultuous period in Iranian history. The British, seeking to safeguard their oil interests represented by the Anglo-Iranian Oil Company (now BP), were notably involved in the 1941 invasion of Iran alongside Soviet forces, leading to Reza Shah's abdication and the installation of his son Mohammad Reza Pahlavi.
The imposition of the Shah's pro-foreign oil policies encountered resistance from Prime Minister Mohammad Mossadegh, who sought to nationalize the oil industry. This move, seen as a threat to Western economic interests, initiated a response from Britain and the US, culminating in the CIA and MI-6 orchestrated coup in 1953 that reestablished the Shah's power. This action set the stage for later conflicts, including the Islamic Revolution of 1979, as foreign intervention and control over natural resources continued to trigger resentment among the Iranian populace.
While the British and Americans considered this a necessary action to maintain the flow of oil and control strategic regions, it created long-standing political and social consequences in Iran. The country's nationalist aspirations were undermined, giving way to tension and instability that ultimately contributed to the rise of the Islamic Revolution and the establishment of an anti-Western government under Ayatollah Khomeini.