BAGHDAD -- The Iraqi army said two drones were destroyed above an Anbar province base housing international coalition forces in the early hours of Sunday (June 6), one month after the same base was targeted by an armed drone.

The US military's C-RAM counter rocket, artillery and mortar system was activated to shoot down the drones above Ain al-Asad base in the western desert, the Iraqi military said.

Several hours earlier, a rocket was shot down above Baghdad airport, "without causing casualties or damage", said international coalition spokesman Col. Wayne Marotto.

The rocket was targeting the Baghdad Diplomatic Support Centre, he said.

Each attack against the Iraqi government, the Kurdish region's administration and the international coalition "undermines the authority of Iraqi institutions, the rule of law and Iraqi national sovereignty", Marotto said.

Since the start of this year there have been 39 attacks against the international anti-"Islamic State of Iraq and Syria" (ISIS) coalition forces in Iraq. The vast majority have been bombs against logistics convoys, while 14 were rocket attacks, some of them claimed by pro-Iran factions.

Previous attacks have been widely blamed on Iran-backed Iraqi militias, with some claimed by a new crop of at least 15 shadowy militias aligned with Iran that have emerged in Iraq over the last year.

These "smokescreen" militias are generally understood to be fronts for the three most prominent Iran-backed militias operating in Iraq: Kataib Hizbullah, Harakat al-Nujaba and Asaib Ahl al-Haq.

Diplomats and high-ranking military officials in Iraq say the attacks compromise the international coalition's fight against ISIS, which retains sleeper cells in mountainous and desert areas.

"Those attacks are a distraction," one such source told AFP.

"The only people they are helping are extremists, because every time they attack a base where the coalition has advisors, those advisors have to stop what they are doing to concentrate on force protection."

The use of unmanned aerial vehicles (UAVs), commonly known as drones, against international anti-ISIS coalition forces by Iran-linked factions is a relatively new tactic.

Iran-aligned Iraqi militias also have been accused of helping the Houthis carry out attacks using drones against Saudi interests from Yemeni soil.