The assault on the Ain Al-Asad base came as pro-Tehran groups hailed the election of Iranian ultraconservative cleric Ebrahim Raisi as the new president of the Islamic republic, with some saying it reflected the "failure" of America's "pawns" in the region.
The attack also comes 10 days after the US offered a reward of up to $3 million for information on strikes against its citizens in Iraq.
US interests in Iraq have come under repeated attack since October 2019, including with rockets, with Washington routinely blaming them on Iran-backed factions.
Since the beginning of the year, a total of 43 attacks have targeted the US embassy in Baghdad, Iraqi bases housing US troops or Iraqi convoys carrying logistical support.
Pro-Iran groups in Iraq are campaigning for the departure of the remaining 2,500 US troops deployed in the country as part of an international coalition to fight the Islamic State group. The Iraqi government declared that fight won in late 2017.
On 10 June the US Department of State's Rewards for Justice programme urged Iraqis with any information concerning anti-American attacks to come forward.
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