The US military on Monday disclosed a more than 50 per cent jump in cases of traumatic brain injury after Iran’s missile attack on a base in Iraq last month.
There are now more than 100 cases of traumatic brain injury, up from the 64 reported last month.
No US troops were killed or suffered external bodily wounds when Iran fired missiles at the Ain Al Asad base in Iraq in retaliation for the death of Revolutionary Guard Corps general Qassem Suleimani in a drone strike at Baghdad airport on January 3.
The missile attacks capped a spiral of violence that started in late December.
Both sides have refrained from further military escalation, but the mounting number of US casualties could increase pressure on the Trump administration to respond.
Army Gen Mark Milley, chairman of the Joint Chiefs of Staff, said last month that the traumatic brain injuries had been diagnosed as mild but the diagnosis could change as time went on.
Symptoms of concussive injuries include headaches, dizziness, sensitivity to light and nausea.
Pentagon officials have repeatedly said there was no effort to minimise or delay information about concussive injuries.
But the disclosures after Tehran’s attack have renewed questions over the US military’s policy on how it internally reports suspected brain injuries and whether they are treated publicly with the same urgency as loss of life or limb.
US President Donald Trump appeared to play down the brain injuries last month, saying he “heard that they had headaches and a couple of other things” after the attack, prompting criticism from politicians and a veterans’ group.
Health groups have for years been trying to raise awareness about the seriousness of brain injuries, including concussion.
Since 2000, about 408,000 service members have had traumatic brain injury diagnosed, Pentagon data shows.