The American invasion of Iraq in 2003 paved the way for Tehran to dominate its neighbor and whetted its appetite to expand its influence across the greater Middle East. In 2008, Qassim Suleimani, then head of Iran’s Quds Force, signaled Iran’s growing clout by telling U.S. commander Gen. David Petraeus that he controlled Iranian policy in Iraq, Syria, Lebanon, Gaza, and Afghanistan.

This message, recounted by Petraeus, marked a turning point in regional dynamics post-9/11. Analysts see it as a milestone in Iran’s emergence as a dominant regional power. The 2003 U.S.-led overthrow of Saddam Hussein removed Iran’s main regional rival, enabling Tehran to fill the power vacuum.

As Stéphane Lacroix of Sciences Po noted, the Iraq war ‘opened the way for this kind of Iranian expansionism.’ Long before 9/11, Iran had sought to overthrow Hussein, but only the U.S. invasion made it possible. The Bush administration’s ‘Axis of Evil’ label, which grouped Iran with Iraq and North Korea, heightened Tehran’s sense of threat, prompting it to counter U.S. influence. Former ambassador Ryan Crocker said Iran became convinced the U.S. was ‘gunning for the regime’ after that speech, accelerating its efforts to challenge American presence in the region.