The Pentagon says 14 more U.S. service members have been diagnosed with traumatic brain injury stemming from a Jan. 8 ballistic missiles attack on U.S. troops at Iraqi air bases, raising the total to 64.

President Donald Trump said in an address to the nation the morning following the attack that, "no Americans were harmed in last night’s attack by the Iranian regime. We suffered no casualties, all of our soldiers are safe, and only minimal damage was sustained at our military bases."

In releasing the latest figures, Pentagon spokesman Lt. Col. Thomas Campbell said 39 service members have returned to duty.

Three of the newly reported cases arrived recently in Germany are undergoing further evaluation, he said. Nine are scheduled to return to the U.S., joining eight who were sent back earlier.

Campbell said 21 of the service members have been transported to Germany for further evaluation and treatment for TBI.

In addition, two service members were awaiting transport to Germany from Iraq, and two others sent to Kuwait for other reasons reasons have been since diagnosed with TBI. They will also be sent to Germany, Campbell said.

The attack by Iran was in retaliation for the killing by U.S. forces of Iranian Maj. Gen. Qassem Soleimani, who was commander of its elite Quds Force.

Gen. Mark A. Milley, Chairman of the Joint Chiefs of Staff, told reporters Thursday that there were thousands of people at Ain al-Asad air base, one of the Iraqi facilities that came under attack.

"All of those people were screened, and we've got a certain number, and then the number's growing," he said, adding that TBI can take time to manifest itself and that screening is continuing.

The latest figures follow sharp criticism of Trump by William "Doc" Schmitz, commander of the Veterans of Foreign Wars, for saying three weeks ago that he "heard that they (some service members) had headaches and a couple of other things, but I would say, and I can report, it's not very serious."

Schmitz has called on Trump to apologize for minimizing the troops' injuries.

"TBI is a serious injury and one that cannot be taken lightly," Schmitz said in a statement. "TBI is known to cause depression, memory loss, severe headaches, dizziness and fatigue — all injuries that come with both short- and long-term effects." He called Trump's comments misguided."

Asked about Trump's comments, Secretary of Defense Mark Esper told reporters, "I've had the chance to speak with the president. He is very concerned about the health and ... welfare of all of our service members, particularly those who were involved in the operations in Iraq, and he understands the nature of these injuries."

“DOD is a leading contributor in the treatment and research of brain-related trauma," he added. "We do everything we can to identify, treat and help our service members recover and return to duty.”

Milley said the Pentagon would "continue to monitor them the rest of their lives, actually, and continue to provide whatever treatment is necessary."

"We take great pride in the fact that these are our own and we're going to take care of them,” he said.

Dr. Mayer Bellehsen is director of the Mildred and Frank Feinberg Division of the Unified Behavioral Health Center for Military Veterans and their Families in Bay Shore, New York.

He said DOD and the Defense and Veteran Brain Injury Center estimate about 20% of combat injuries from Iraq and Afghanistan are brain injuries.

"They are so prevalent that it is often considered a 'signature wound' of the recent conflicts," said Bellehsen in emailed comments, noting they can be caused by blasts, motor vehicle accidents and gunshot wounds.

People who suffer injuries classified as "mild" often recover in weeks, while "moderate" and "severe" cases require longer term follow up and treatment.

"However, with proper treatment and healthy behaviors, many people will recover in time," he said.