Iranian news agency Mehr said Iran’s Islamic Revolutionary Guard Corps had targeted the base. Tehran has vowed retaliation for the killing of Iranian military commander Qassem Soleimani.

It was not immediately clear what the extent of damage or casualties was at the base.

US President Donald Trump has been briefed on reports of an attack on US facilities in Iraq and was monitoring the situation, White House spokeswoman Stephanie Grisham said.

Earlier on Tuesday, U.S. Defense Secretary Mark Esper said the United States should anticipate retaliation from Iran over the killing in Iraq of Soleimani, commander of the elite Quds Force.