"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 blasts and are still being assessed," US Central Command spokesman Captain Bill Urban said in a statement on Thursday.
On January 8, the Islamic Revolution Guards Corps (IRGC) fired volleys of ballistic missiles at Ain al-Asad, a large airbase hosting about 1,500 US troops, and another outpost in Erbil, the capital of the semi-autonomous Iraqi Kurdistan.
The missile operation was in response to Washington's January 3 assassination of top Iranian general Qassem Soleimani, who led the IRGC’s Quds Force.
The assassination also resulted in the death of Abu Mahdi al-Muhandis, who was the second-in-command of Iraq’s Popular Mobilization Units (PMU).
Speaking on the morning following Iran's reciprocal military operation, US President Donald Trump had said that "no Americans were harmed in last night’s attack".
"We suffered no casualties, all of our soldiers are safe, and only minimal damage was sustained at our military bases," he added.
The Pentagon had also initially ruled out any casualties from the attack.
Speaking on Thursday, however, Urban said US soldiers injured from the Iranian missile strikes had been taken to US bases outside Iraq for further treatment "out of an abundance of caution".
"At this time, eight individuals have been transported to Landstuhl, and three have been transported to Camp Arifjan," he said, referring to Washington's Landstuhl Regional Medical Center in Germany and Camp Arifjan in Kuwait.
The development marks the latest report in a string of recent revelations undermining initial US claims downplaying casualties and damage following Iran's retaliatory missile attack.
Reports and satellite images have gradually revealed what US media have described as "extensive" damage at the base.
On Wednesday, the AFP reported that US drone operators stationed in Ain al-Asad had lost access to US military drones for about nine hours after the base sustained damage during the Iranian missile strikes.
Speaking on Thursday, head of the Aerospace Division of the Islamic Revolution Guards Corps (IRGC) Brigadier General Amir Ali Hajizadeh said dozens of US troops had been killed and injured in the operation.
According to Hajizadeh, the US military conducted at least nine sorties of C-130 flights after the missile strikes, taking wounded personnel to Jordan and Israel while Chinook helicopters transferred the injured to the US hospital in Baghdad.
'Daesh delighted about Soleimani assassination'
Many observers have highlighted that Washington's provocations in Iraq, notably the assassination of Gen. Soleimani, benefits Daesh in Iraq.
Earlier this week, the leading US daily New York Times said that the assassination had "delighted" the foreign-backed terrorist group.
The report said the assassination could lead to the further destabilization of the country and create room for the terrorist group's reemergence.
"General Soleimani’s death will have its (Daesh) leaders rubbing their hands in anticipation," for a resurgence, the newspaper said.
General Soleimani played a major role in advising Iraqi forces to successfully push back Daesh after the terror group swept over large parts of the country in 2014.
After being vanquished in Iraq, the terrorist group's presence is currently limited to dispersed cells operating in more remote areas of the country.