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The total number of U.S. soldiers injured in this month’s round of retaliatory missile attacks by Iran has risen to 64, Defense Department officials announced Thursday, despite initial claims from the White House and the Pentagon that there were no casualties.

The injured soldiers have been diagnosed with traumatic brain injuries (TBIs), and of the 64 diagnosed, 39 have already been treated and returned to duty, according to the military newspaper Stars and Stripes.

“Your brain is a very fragile part of your body,” Army Gen. Mark Miller, the chairman of the Joint Chiefs of Staff, told reporters in a Thursday news conference. “The unseen wounds of war can be serious and not serious. It depends on the individual and their proximity to the blast.”

In the initial aftermath, Trump said that no Americans were hurt as a result of the missile attacks. Following the disclosure that some soldiers were, in fact, hurt, Trump waved off the injuries as “headaches and a couple of other things,” and said he didn’t “consider them very serious relative to other injuries that I’ve seen.”

Defense Secretary Mark Esper defended Trump’s assessment on Thursday, according to Stars and Stripes. “The reporting was accurate, at that time,” Esper told reporters, adding that Trump “is very concerned about the health and welfare of all of our service members, particularly those who were involved in the operations in Iraq.”

Following Trump’s comments last week downplaying the injuries, the Veterans of Foreign Wars—which has clashed with Trump in the past—demanded an apology, noting that TBIs have been recognized as a factor in long-term health problems.

“TBI is a serious injury and one that cannot be taken lightly,” VFW commander Doc Schmitz said in a statement last week. “The VFW expects an apology from the president to our service men and women for his misguided remarks.”