The United States military achieved every objective it set when it went to war in Iraq in 2003. Decapitation: Saddam Hussein was captured, tried and hanged. Air dominance: total, within days. Regime collapse: The Iraqi government fell in 21 days.

ERBIL, Kurdistan Region - Iraqi Prime Minister Mohammed Shia’ al-Sudani stressed the need for de-escalation and diplomacy during a phone call with NATO Secretary General Mark Rutte, warning against the widening of the war against Iran,

Iran has spent decades and billions of dollars building a network of proxy militias in Iraq. But as Tehran now faces what many see as an existential threat amid its war with the United States and Israel, many of those fighters have yet to join the conflict.

President Trump's war against Iran carries echoes of the 2003 war in Iraq. NPR's Leila Fadel explores the lessons learned to understand whether regime change stands a chance in neighboring Iran.