The American economy’s chronic addiction to cheap oil is obvious. Less well known is the story of when that addiction began and why the United States became so reliant in particular on Saudi Arabia for its continued goodwill and cooperation. The same is true of America’s toxic relationship with Iran. The two countries have been at each other’s throats for so long now that it seems hard to believe they were ever allies—let alone partners in a secret contingency plan to invade Saudi Arabia and seize its oil wealth. Until these tensions are resolved, and until both countries come to terms with their complicated shared history, it seems inevitable that the tree of American-Iranian relations will bear poisoned fruit for many years to come.