U.S. President Donald Trump on Wednesday said he did not consider the brain injuries suffered by 11 U.S. service members in Iran's recent attack on a base in Iraq to be serious, as the American military moved more troops out of the region over potential injuries.

In a statement on Wednesday, U.S. Central Command said more troops had been flown out of Iraq to Germany for medical evaluations following Iran's January 8 missile attack on the base where U.S. forces were stationed after announcing the 11 injuries last week.

Further injuries may be identified in the future, it added, without giving further details.

A U.S. official, speaking on condition of anonymity, said about a dozen troops were being transported to Germany.

Trump and other top officials initially said Iran's attack had not killed or injured any U.S. service members before the Pentagon reversed course on Thursday, saying 11 U.S. troops had been treated for concussion symptoms after the attack on the Ain al-Asad air base in western Iraq.

On Wednesday, Trump declined to explain the discrepancy.

"I heard that they had headaches and a couple of other things, but I would say and I can report it is not very serious," Trump told a news conference in Davos, Switzerland.

Asked whether he considered traumatic brain injury to be serious, Trump said: "They told me about it numerous days later. You'd have to ask the Department of Defense."

Pentagon officials have said there had been no effort to minimize or delay information on concussive injuries, but its handling of the injuries following Tehran's attack has renewed questions over the U.S. military's policy regarding how it handles suspected brain injuries.

While the U.S. military has to immediately report incidents threatening life, limb or eyesight, it does not have an urgent requirement to do so with suspected traumatic brain injury, or TBI, which can take time to manifest and diagnose.

According to Pentagon data, about 408,000 service members have been diagnosed with traumatic brain injury since 2000.

Various health and medial groups for years have been trying to raise awareness about the seriousness of brain injuries, including concussions.

"I don't consider them very serious injuries relative to other injuries I have seen," Trump said. "I've seen people with no legs and no arms."

In Washington, a senior military official said that the number of U.S. troops who had been flown out of Iraq was in the "teens."

U.S. Air Force Major General Alex Grynkewich, deputy commander of the coalition fighting Islamic State in Iraq and Syria, added that while some counter-ISIS (ISIL) operations in Iraq had resumed, they were still on a limited scale.