At least two fighters belonging to Iraq's paramilitary groups have been killed in strikes near the border with Syria.
They were killed by drones about 15 kilometres away from the border, the Anbar paramilitary operations command said on Sunday.
One struck the headquarters of a local paramilitary brigade and the other a convoy of cars leaving the building.
Officials from the Hezbollah Brigades, separate from the Lebanese group of the same name, said the drone attack occurred near the Qaim border crossing.
They said that the attack targeted vehicles belonging to the Hezbollah Brigades faction, also known as Brigade 45.
A military source from Hezbollah Brigades told AFP that one of the dead, Abu Ali Al Dabi, was a member of the unit's rocket squad.
"He fought in Syria and was previously detained by the Americans," the source said.
The vehicles were understood to be used to transport weapons.
Chief of the Hashed Al Shaabi force and Iraqi National Security Adviser Faleh Al Fayyadh said early investigations found the attacks were premeditated, but he has not revealed the perpetrators.
Mr Al Fayyadh's deputy Abu Mehdi Al Muhandis blamed Washington for the attack.
Sunday's attack happened after a series of explosions in recent weeks at weapons depots belonging to Iran-backed militias in Iraq.
The militias have blamed Israel and the US for some of the attacks. Israel has hinted at its involvement but the Pentagon has denied responsibility.
The recent attacks have sparked fears that tension between Iran, Israel and the US are spreading to Iraq.
Israel fears that Iran could transfer weapons to allies in Iraq, Syria and Lebanon that could be used to attack it. To try to reduce the level of threat, Israel has carried out hundreds of strikes against Iranian forces and their allies in neighbouring Syria.
But the brigades also blame the US for the attacks. On Thursday, the group issued a "final warning" to the US over the purported attacks.
"We issue a final warning to the American enemy that any new targeting of any Iraqi positions will be met with a tough, categorical response," it said in a statement.
Iraq's Hezbollah Brigades operate under the umbrella of the state-sanctioned militias known collectively as the Popular Mobilisation Forces. Many of them are supported by Iran.