At least five rockets hit the Iraqi military air base at Balad north of Baghdad on Sunday, wounding two Iraqi soldiers, the Iraqi military said in a statement.
Security officials had said earlier that the Katyusha rockets had fallen on the area of the base that houses US contractors, and that no casualties had been reported.
The last attack on the base was on April 4, when at least two rockets fell in the sparsely populated surrounding area.
No group immediately claimed the attack, but armed groups that some Iraqi officials say are backed by Iran have claimed similar incidents in the past.
US officials have blamed Iranian-backed militias for regular rocket attacks aimed at US facilities in Iraq, including the US Embassy in Baghdad.