The U.S. troops withdrew from Iraq in 2011, eight years after the U.S.-led invasion. U.S. troops returned to the country in 2014 to support the Iraqi forces in the fight against the Islamic State militants.
Immediately after the deaths of top Iranian general Qassem Soleimani and Iraqi militia leader Abu Mahdi al-Muhandis in a U.S. airstrike at Baghdad airport in Jan. 2020, the Iraqi parliament passed a resolution requiring the government to end the presence of foreign forces in Iraq.
Iraqi military bases housing U.S. troops across the country and the U.S. embassy in the Green Zone in central Baghdad have been frequently targeted by rocket and drone attacks from Iran-backed Shia militias.
The U.S. military launched retaliatory airstrikes against Shia militants in Syria and Iraq this February and June, only leading to a cycle of more attacks and reprisals.
Earlier this month, up to 14 rockets hit Al-Assad Air Base housing U.S.-led coalition forces in Iraq's western province of Anbar, causing two minor injuries.