The Pentagon said Friday that 34 U.S. service members were diagnosed with varying degrees of brain injuries after Iran's ballistic missile attack in Iraq this month, an increase in the number of troops known to have been hurt in the explosions. 

President Donald Trump said the morning after the Jan. 8 attack that no U.S. troops were harmed. But defense officials have said information about injuries was not relayed to Washington until later because no service members suffered loss of life, limb or eyesight.

On Wednesday, Trump downplayed the significance of the brain injuries.

"I heard that they had headaches and a couple of other things," he said. "But I would say, and I can report, it is not very serious, not very serious."

The Pentagon's chief spokesman, Jonathan Hoffman, told reporters during a news conference Friday that the service members were diagnosed with "concussions and TBI," or traumatic brain injury.

Eight service members who were removed from Iraq for additional treatment at Landstuhl Regional Medical Center in Germany have returned to the United States for more medical care, while nine others remain in Germany, Hoffman said. The remaining 17 who were diagnosed with concussions, a mild form of TBI, have been returned to duty, he said.

All of those still receiving care are doing so with outpatient status, Hoffman said. Some will be sent to Walter Reed National Military Medical Center outside Washington, while others will return to their home bases.

The Defense Department is "committed to delivering programs and services intended to lead to the best possible outcomes for our service members who suffer any injury," Hoffman said. "Over the last two weeks, we have seen a persistent and dedicated effort by our medical professionals in Iraq, Kuwait and Germany to diagnose any and all members who need assistance."

Iran launched the ballistic missile attacks in retaliation for the U.S. killing of Iranian Maj. Gen. Qassem Soleimani in a drone strike in Baghdad. Eleven missiles hit al-Asad air base west of Baghdad, leaving wreckage and deep craters at a facility where more than 1,000 U.S. service members were based along with Iraqi forces. Another missile landed outside the northern city of Irbil, but resulted in less damage.

At least one of the missiles at al-Asad struck just yards from a bunker with a service member in it, Maj. Gen. Alex Grynkewich, a senior U.S. commander for the U.S. mission in Iraq and Syria, said Wednesday.

On Jan. 13, U.S. military officials told reporters visiting al-Asad that "dozens" of service members were suffering from concussion-like symptoms. But updates have been vague, with officials declining to answer questions until Friday about whether anyone needed to return to the United States for additional treatment or if anyone had returned to duty.

Hoffman said that Defense Secretary Mark Esper on Friday directed a new review of the processes for tracking who is wounded or injured in action. The goal, Hoffman said, is to be accurate and transparent with the American people.