Eleven American troops were treated for concussions after Iranian missiles struck two Iraqi bases where the servicemembers were stationed, the military said on Thursday, contradicting earlier statements by President Trump that no Americans had been injured.

The Jan. 8 attack on bases near Baghdad and Erbil, Iraq, were launched in retaliation for the killing of Maj. Gen. Qassim Suleimani, a senior figure in Iran’s military, in a drone strike ordered by Mr. Trump.

“While no U.S. servicemembers were killed in the Jan. 8 Iranian attack on Al Asad air base, several were treated for concussion symptoms from the blast and are still being assessed,” Capt. Bill Urban, a spokesman for United States Central Command, said in a statement.

In a speech, Mr. Trump had said that no Americans were hurt in the strike, in which at least a dozen missiles were fired.

“I’m pleased to inform you the American people should be extremely grateful and happy,” the president said on Jan. 8. “No Americans were harmed in last night’s attack by the Iranian regime.”

Captain Urban said the injured troops were taken to American military sites in Germany and Kuwait to undergo screening, and that “when deemed fit for duty, the servicemembers are expected to return to Iraq.”

The lack of American deaths in the strikes was a welcome relief to American officials, who had feared General Suleimani’s killing could set off a larger regional conflict. By Jan. 9, the day after the strike, both countries had publicly said they would de-escalate direct military action.

The general’s death and the subsequent missile strike, however, set other events in motion, including the accidental downing of a Ukrainian passenger jet in Tehran by the Iranian military, in which 176 people were killed, and a resolution by the Iraqi Parliament calling for the expulsion of foreign forces from the country.