US personnel suffered minor injuries and a member of Iraq's security forces was seriously wounded in an attack on Iraq's Ain al-Asad air base on Saturday, a US official said.
The official, who spoke on condition of anonymity, said initial reports indicated that the base was hit by ballistic missiles but he left open the possibility it was struck by rockets. An assessment was ongoing, the official said.
Two security sources in Iraq and one government source said the base was hit by multiple rockets fired from inside Iraq.
A second US official said the attack was carried out by militants from inside Iraq.
Since the Israel-Hamas war began in October, the US military has come under attack at least 58 times in Iraq and another 83 times in Syria by Iran-backed militants, usually with a mix of rockets and one-way attack drones.
The militants are seeking to impose a cost on the United States for its support of Israel against Iran-backed Palestinian militant group Hamas.
US troops in Iraq
The US has 900 troops in Syria and 2,500 in Iraq on a mission to advise and assist local forces trying to prevent a resurgence of Islamic State, which in 2014 seized large parts of both countries before being defeated.
Iraq is deeply concerned about becoming a battleground between the United States, Israel and Iran.
Iraq's Prime Minister Mohammed Shia al-Sudani's office announced moves to evict US forces following a US drone strike in Baghdad that was condemned by the government. The Pentagon said the strike killed a militia leader responsible for recent attacks on US personnel.
The Pentagon said it has not been formally notified of any plans to end the US troop presence in the country, and says its troops are deployed to Iraq at the invitation of the government in Baghdad.
Iran on Monday struck Erbil, the capital of Iraq's semi-autonomous Kurdistan region, with ballistic missiles in what it said was an attack on an Israeli spy headquarters -- claims denied by Iraqi and Iraqi Kurdish officials.