At least 11 service members were injured during Iran's January 8 attack against Al Asad airbase, according to United States Central Command spokesperson Captain Bill Urban. "Several were treated for concussion symptoms from the blast and are still being assessed," Urban said, after the Iraqi military bases housing around 1,500 troops were hit by missiles.

"In the days following the attack, out of an abundance of caution, some service members were transported from Al-Asad airbase, Iraq to Landstuhl Regional Medical Center in Germany, others were sent to Camp Arifjan, Kuwait, for follow-on screening," Urban said, in a statement obtained by CBS News.

Eight service members were transported to Landstuhl while three were transported to Camp Arifjan. A statement obtained by CBS News from the Department of Defense confirmed that "several were treated for concussion symptoms."

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Iran launched a barrage of ballistic missiles at the military bases last week in retaliation for the killing of senior Iranian military commander Qassem Soleimani during a January 2 drone strike in Baghdad. Officials in Tehran have said their forces were on high-alert for any U.S. response to the missile attack.

Iran's attack on the bases killed no one, but U.S. officials have dismissed speculation that Iran might have deliberately missed the troops in a bid to prevent further escalation of hostilities.

—David Martin contributed reporting.