U.S. Airpower Joins Iran-Backed Offensive in Iraq’s Tikrit

The U.S. and allies began airstrikes on the Iraqi city of Tikrit, where Iranian-backed Shiite militias have been fighting to expel Islamic State fighters from the largely Sunni Muslim area.

The strikes effectively make the U.S. an unacknowledged partner of Iran, an alliance that American officials have disavowed even as the two nations work in parallel against the terrorist group.