The Pentagon said on Tuesday 50 US service members were now diagnosed with traumatic brain injury after missile strikes by Iran on a base in Iraq earlier this month, 16 more than the military had previously announced.
President Donald Trump and other top officials initially said Iran's Jan. 8 attack had not killed or injured any US service members.
"As of today, 50 US service members have been diagnosed" with traumatic brain injury, Pentagon spokesman Lieutenant Colonel Thomas Campbell said in a statement about injuries in the attack on the Ain al-Asad airbase in western Iraq.
Symptoms of concussive injuries include headaches, dizziness, sensitivity to light and nausea.
Thirty-one of the 50 were treated in Iraq and returned to duty, including 15 of those diagnosed most recently, Campbell said.
Eighteen of the total have been sent to Germany for further evaluation and treatment, and one was sent to Kuwait and has since returned to duty, he said.
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"This is a snapshot in time and numbers can change," Campbell said.
In its previous update on Friday, the Pentagon had put the number of those injured at 34.
Trump last week appeared to play down the injuries, saying he "heard that they had headaches and a couple of other things."
That prompted criticism from a US war veterans group. William Schmitz, national commander of the Veterans of Foreign Wars, said on Friday the group "expects an apology from the president to our servicemen and women for his misguided remarks."
According to Pentagon data, about 408,000 service members have been diagnosed with traumatic brain injury since 2000.
Iran fired missiles at Ain al-Asad in retaliation for the US killing of a top Revolutionary Guard general, Qassem Soleimani, in a drone strike at Baghdad airport on Jan. 3.
The missile attacks capped a spiral of violence that had started in late December, and both sides have refrained from further military escalation.