Two rockets were fired at a military base near Baghdad airport housing US troops, the 10th such attack since late October, the Iraqi army said on Thursday.

Axar.az reports citing Alarabiya that there were no casualties in the overnight attack, which follows one on the same base on Monday which wounded six members of Iraq’s elite US-trained counterterrorism force, two of them critically, the army said.

Washington has expressed mounting concern about the flurry of attacks on US bases and diplomatic missions, several of which it has blamed on Shiite militia groups trained by its foe and rival for influence Tehran.

Security sources have linked at least one attack last week to Kata’ib Hezbollah, a powerful Shiite faction close to Tehran and blacklisted by Washington.

Iran holds vast sway in Iraq, especially among the more hardline elements of the Popular Mobilization Units militias (PMU, known in Arabic as the Hashed al-Shaabi), a paramilitary force largely made up of Shiite militias.