BAGHDAD, Jan. 8 (Xinhua) -- Iran fired missiles Wednesday at Iraqi military airbase, which houses U.S. troops in Iraq's western province of Anbar, a provincial security source said.

Ayn al-Asad airbase in al-Baghdadi area, some 190 km northwest of the Iraqi capital Baghdad, was pounded with more than 20 ballistic missiles before dawn, the source from the Iraqi army told Xinhua on condition of anonymity.

There were no immediate reports about casualties, the source said, adding that sirens were heard inside the airbase, while U.S. helicopters flew over the area.

The Iranian attack came three days after the Iraqi parliament passed a resolution requiring the government to end the presence of foreign forces in Iraq and prevent them from using Iraqi airspace and waters.

On Friday, a U.S. drone attacked a convoy at Baghdad International Airport, killing Qassem Soleimani, commander of the Quds Force of Iran's Islamic Revolution Guard Corps, and Abu Mahdi al-Muhandis, deputy chief of Iraq's paramilitary Hashd Shaabi forces.

More than 5,000 U.S. troops have been deployed in Iraq to support the Iraqi forces in the battles against Islamic State militants, mainly providing training and advising for the Iraqi forces.