For PBS NewsHour, Reza Sayah and Gelareh Kiazand investigate U.S. claims of Iran’s interference in Iraq and Iran’s rising religious, political, and security presence there. Today, Washington and its Gulf Arab allies are alarmed at Iran’s growing influence in Iraq. The U.S. accuses Iran of destabilizing Iraq and meddling in its affairs. News headlines often echo this view. Iran’s perceived interference in Iraq is used by Washington to determine and justify policy, e.g., increased sanctions against Iran, closer ties to Saudi Arabia to counter Iranian influence, increased spending to boost US influence in Iraq. How far has Iran extended its reach in Iraq and what are its intentions? And are U.S. concerns justified? Sayah and Kiazand also look at how the United States tacitly teams up with archrival Iran to defeat ISIS, and why this rare event that seemingly helped Iraq is not a sign of things to come.