In the early hours of January 8, Tehran retaliated for the US's murder of Iran's most powerful general by bombing al-Asad Air Force Base in Iraq.
Among the 2,000 troops stationed was the U.S. Army Specialist, Kimo Keltz, who remembers hearing a missile whistle through the sky as he lay on the deck of a watchtower. The explosion lifted his body – in full armor – an inch or two off the ground.
Keltz says he thought he only got away with a slight headache. Initial surveys around the base did not reveal any serious injuries or deaths from the attack. US President Donald Trump tweeted: "Everything is good!"
The next day was different.
"My head felt like I was hit by a truck," said Keltz Reuters in an interview from al-Asad Air Force Base in the western Anbar desert of Iraq. "My stomach grated."
Keltz, who said he had had concussion symptoms for days, is among the 109 soldiers who were diagnosed with traumatic brain injuries after the attack last month. This number has increased steadily as more troops report symptoms and undergo a medical examination.
Reuters interviewed more than a dozen officers and soldiers and spoke to brain injury specialists to produce the most comprehensive report on how soldiers have been injured and how they have been sustained.
The slow rise in casualties underscores the difficulty in identifying and treating one of the most common violations by the U.S. military during the two-decade war in Afghanistan and Iraq, in which U.S. troops face roadside bombs, missiles, and mortars ,
More than a week after the January 16 attack, Secretary of Defense Mark Esper was warned that the missiles had caused brain injuries to soldiers, the Pentagon said. That day, the Pentagon reported that an unspecified number of troops were being treated for concussion symptoms and 11 were being flown to Kuwait and Germany for primary care.
On January 22, Trump said he had "heard that they had a headache and a few other things," which generated criticism from both Democratic and Republican lawmakers and a U.S. veteran group that the president underestimated the victims of the attack.
"I think it was unfortunate to use these words," said Republican Representative Richard Hudson, who represents Fayetteville, North Carolina, home of Fort Bragg, which includes the Army Special Operations Command.
The White House declined to comment on this story.
Another class of wounds
The U.S. military has long treated brain injuries as another class of wounds that, unlike incidents that threaten lives, limbs, or eyesight, do not require a rapid chain of command reporting.
According to the Pentagon, nearly 414,000 service members have been diagnosed with traumatic brain injuries (TBIs) since 2000. The number is likely to be higher, as the Pentagon only counts as one injury case in which a soldier suffers brain trauma in several incidents.
US troops flying drones appeared to have suffered the most brain injuries during the attack on al-Asad, said Lt. Col. Timothy Garland, who was on the base at the time. Many worked near the airstrip, he said. Like specialist Keltz, who occupied a watchtower, the drone pilots had been commissioned to watch out for a possible ground attack.
"These drone pilots have borne the brunt of the TBI cases," said Garland, who oversees more than 400 soldiers as commander of the Jazeera task force.
The number of troops diagnosed with a brain injury due to the attack last month is expected to stabilize near the current number, a US official said. Less than 10 have now been monitored for possible TBI symptoms, the official said.
The total number of U.S. military personnel, however, excludes civilian contractors on the base, many of whom have since departed.
Some US troops also suffered from anxiety symptoms, including insomnia and, in at least one case, a persistent high heart rate after the attack. This emerges from interviews with soldiers and officials. However, they were unable to provide a specific number.
The Pentagon categorizes brain injuries as mild, moderate, severe, or penetrating. The vast majority of injuries are classified as minor, as are all injuries reported by al-Asad.
Garland, the commander, said he was taken aback when he learned of U.S. intelligence that indicated that Iranian missiles would strike within a few hours. He immediately found a basemap and began to find the best ways to protect his troops.
He remembered old base bunkers built in the days of Saddam Hussein, the Iraqi dictator who was overthrown by US forces in 2003. But the bunkers wouldn't all hold. Some would have to disperse and hide in armored vehicles driven away from targets.
Others in Garland's unit – including Specialist Keltz – would have to be on guard to watch out for additional attacks beyond the expected missiles.
Keltz said he and a fellow soldier were already occupying a tower when First Sergeant Larry Jackson came to them, told the secret service and gave them their orders.
"I need you guys to lie down on the ground when the effects come – and then you'll have to jump back up and man these weapons," Jackson said in an interview, telling Keltz and other soldiers his instructions at the root.
As the Iranian missiles flew through the night sky to the base, their engines glowed orange – like the ends of lit cigarettes, Garland said. The glow was all Garland could see in the dark before crawling back into a bunker.
Then the explosions came. At least eleven missiles hit the base and destroyed residential units from shipping containers and other facilities.
"Every explosion I heard I thought, OK, there are a number of people who have just lost their lives," he said.
However, initial checks after the attack revealed that despite massive devastation at the base, no one was killed or apparently injured. The message came back to Washington. Shortly before 6 a.m. in Baghdad, Trump tweeted an update: "Evaluation of the victims and damage that are now taking place. So far, so good!"
Fall through the cracks
On site in al-Asad, U.S. Army Major Robert Hales, a doctor based in al-Asad, defended the first reports of no injuries.
"Everyone here had no physical injuries," he said in an interview. "There were no cuts. There are no splinters."
Such "silent" injuries take time to manifest, he said.
In the weeks after the attack, the number of injuries continued to increase. What started as at least 11 cases grew to 34 about a week later.
On January 22, Trump made his controversial comment, calling the injuries "headaches." The Veterans of Foreign Wars apologized for Trump's "misguided remarks".
A week later, on January 28, the number of brain injuries increased to 50. In early February, Reuters was the first to report that the number had exceeded 100.
The brain injuries sustained in the Iranian missile attack are fundamentally different from those that typically result from previous attacks, brain trauma specialists said.
This is because the Al-Asad bombing raids were more intense than typical one-shot hits: the explosions came in waves and lasted more than an hour.
Head injuries are often visible when a bomb goes off on the roadside in Afghanistan. In the event of insurgent bomb explosions, splinters or other flying debris can cause brain injuries on impact. But the damage caused by large pressure waves caused by a large explosion – like that of specialist Keltz at al-Asad – often takes more time to diagnose.
Marilyn Kraus, director of the Traumatic Brain Injury Program and Concussion Clinic at George Washington University, said troops may initially minimize or report their symptoms. Others may not show symptoms until much later, in part because their injuries are initially masked by the adrenaline rush that comes with the fight.
"Some of these things can initially fall into the cracks," said Kraus, who previously served as medical director of the Traumatic Brain Injury Advisory Department at Walter Reed Military Hospital in Bethesda, Maryland.
In the short term, a minor traumatic brain injury can cause headaches, nausea, dizziness, and confusion, while the longer-term effects can be chronic headaches, mood swings, and dizziness, Kraus said. Repeated head injuries can lead to chronic traumatic encephalopathy, a brain degeneration disorder that some researchers have associated with suicidal thoughts, substance abuse, and depression, she said.
Hales, the military doctor, cited research in the past six months that animal models showed that signs of brain damage can increase in the weeks after an explosion. In al-Asad, soldiers showed symptoms such as headache or a "foggy feeling" days after the attack, Hales said. The symptoms often persisted.
"That's why you saw a big delay in identifying the injuries," he said. "That prompted us to re-examine pretty much the entire population of al-Asad."
(Except for the headline, this story was not edited by NDTV staff and published from a syndicated feed.)