BREAKING: Rockets fired at US troops in Iraq, Syria

There were no casualties as a result of these three attacks. Monday was the anniversary of the killing of Qassim Soleimani, who was targeted by the US two years ago in an airstrike. General Frank McKenzie, top US commander for the Middle East, said only a month ago that he anticipated further attacks from Iran-backed groups seeking to dislodge the US from Iraq.

After Soleimani's death, Shiite factions in Iraq made their intentions for revenge and retaliation against the US clear, saying that they intended to fight until the US left the country.

Five rockets hit the base in western Anbar, while three of the Katyusha rockets were just off target, landing outside the perimeter of the base. The Iraqi officer who gave this information to the AP spoke on condition of anonymity, they reported, which is per regulations.

US and coalition forces took shelter during the attack. Pentagon Press Secretary John Kirby said "We’re very mindful of the threat environment and it is very dynamic right now."

"The Coalition reserves the right to defend itself and partner forces against any threat," Maj. Gen. John W. Brennan, Jr., commander of the joint task force said, "and will continue to do everything within its power to protect those forces."

As to who is responsible for the attack, a group called Qassem al-Jabarayn claimed responsibility for the Ain al-Asad attack, and this group was previously not on the radar of US officials, the AP reports.

However, since Soleimani was killed in a US airstrike, "Iran-backed militias in Iraq," the AP reports, "have become increasingly unruly and disparate." There is a suspicion that the multiple militias are merely a rouse to make it seem like there are more groups gunning for the US-led coalition in Iraq.

The combat mission of the US-led coalition in Iraq ended last month, leaving 2,500 troops on hand to facilitate the transition to an "advisory mission" in support of Iraqi forces.