As the U.S.-Israel war in Iran surges on, it’s hard to imagine Iran was once an important U.S. ally.

Iran was the United States' best ally in the Middle East,” said Ali Vaez, the Iran project director at the International Crisis Group. “It was really a linchpin of U.S. policy in the region,” but he noted the countries have “a very complicated history.”

Friendly relations between the United States and Iran can be traced back to 1953, when the United States and the United Kingdom helped stage a coup against Iran’s then-prime minister, Mohammad Mosaddegh, over concerns about Mosaddegh’s attempt to nationalize the country’s oil industry and fears that it would draw the influence of the Soviet Union. The coup would return the last Shah of Iran, Mohammad Reza Pahlavi, to power, with support from the United States.

The United States and Iran remained on friendly terms, for the most part, over the next two decades. The United States sold weapons and provided military support to Iran as it resisted the Soviet Union, and both countries embarked on a cultural exchange to improve higher education in Iran.

“There was a lot of back and forth with Iranian students studying in the United States and returning home to try to help develop their own country,” Vaez said.