As the US weighs joining Israel’s assault on Iran, questions are mounting over whether such an intervention could trigger regime change in Tehran – an outcome that risks splintering the country and sending shockwaves across the region.

Over the next three decades, Khamenei turned Iran around into as assertive power wielding influence across the Middle East. One major boost was the U.S.’s 2003 ouster of Saddam Hussein, which eventually brought Iranian-allied Shiite politicians and militias to power in Iraq.