Washington: The United States treated 11 of its troops for symptoms of concussion after an Iranian missile attack on an Iraqi base where US forces were stationed, the US military said on Thursday, after initially saying no service members were hurt.

A US soldier stands while bulldozers clear rubble and debris at Ain al-Asad air base in Anbar, Iraq, Monday. Credit:AP

The attack was retaliation for a US drone strike in Baghdad on January 3 that killed Qassem Soleimani, the commander of the elite Quds Force of Iran's Revolutionary Guard.

US President Donald Trump and the US military had said there were no casualties after the strike on the Ain al-Asad air base in western Iraq and a facility in its northern Kurdish region.

"While no US service members were killed in the January 8 Iranian attack on Al Asad air base, several were treated for concussion symptoms from the blast and are still being assessed," Captain Bill Urban, spokesman for US Central Command, said in a statement.