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WASHINGTON — Thirty-four U.S. service members were diagnosed with concussions and traumatic brain injuries following Iranian airstrikes on the Ain al-Asad Air Base in Iraq earlier this month, the Pentagon's chief spokesman said Friday.

Iran fired more than a dozen ballistic missiles at two Iraqi air bases on Jan. 8 in retaliation for the U.S. killing of Gen. Qassem Soleimani, an influential and powerful Iranian military commander.

Jonathan Hoffman, the Pentagon spokesman, confirmed Friday that eight of the U.S. service members who received diagnoses were transported to a hospital in Germany and then taken back to the United States, where they will receive treatment at the Walter Reed Medical Center. He said another nine were still in Germany.

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Seventeen of the service members who were diagnosed with concussions and traumatic brain injury, or TBI, were back on active duty in Iraq, Hoffman told reporters.

No one was killed in the attack on the Ain al-Asad Air Base in western Iraq.

Trump appeared to downplay the severity of those injuries at a news conference Wednesday after the Pentagon acknowledged that U.S. troops were being examined for injuries resulting from the Iranian airstrikes.

"I heard they had headaches," Trump told reporters in Davos, Switzerland. "I can report it is not very serious."

"No, I don't consider them very serious injuries relative to other injuries that I've seen," Trump said. "I've seen what Iran has done with their roadside bombs to our troops. I've seen people with no legs and with no arms. I've seen people that were horribly, horribly injured in that area, that war."

The killing of Soleimani by an American drone strike in Baghdad on Jan. 3 sharply escalated tensions between the U.S. and Iran, raising fears in both countries of a potential military conflict.

Hoffman said the Department of Defense was "committed to delivering programs and services intended to lead to the best possible outcome for our service members who suffer any injury."

Mosheh Gains reported from Washington, Daniel Arkin reported from New York.