Drones and rockets targeted on Thursday evening the Ain al-Asad air base, which hosts US and other international forces in western Iraq, and multiple blasts were heard inside the base, two security sources said.
The Iraqi military said it closed the area around the base and started a search operation. It was not clear yet whether the attacks caused casualties or damages, said the sources.
Thursday's attack is the third in less than 24 hours against airbases which house US troops in Iraq.
US military forces in Iraq were targeted on Wednesday in two separate drone attacks, with one causing minor injuries to a small number of troops even though the US military managed to intercept the armed drone.
Threats of targeting the US
Last week, Iraqi armed groups aligned with Iran threatened to target US interests with missiles and drones if Washington intervened to support Israel against Hamas in Gaza.
The United States has 2,500 troops in Iraq, and 900 more in neighboring Syria, on a mission to advise and assist local forces in combating Islamic State, which in 2014 seized swathes of territory in both countries.
Ain al-Asad air base is located in the western Anbar province.