The United States military says 11 American soldiers were injured in an Iranian missile strike on an Iraqi base.
A spokesman confirmed several members of personnel were treated for "concussion symptoms" after the attack on Al Asad air base last week and "are still being assessed".
The US had previously stated that none of its military personnel were hurt, while the UK's Ministry of Defence now says no British personnel were present at the site during the time of the attack.
A statement released by Captain Bill Urban, a spokesman for US Central Command, said eight individuals were sent to a medical centre in German for follow-up brain trauma screening.
Three Americans were also transported to Kuwait.
"As a standard procedure, all personnel in the vicinity of a blast are screened for traumatic brain injury, and if deemed appropriate are transported to a higher level of care", the statement read.
"In the days following the attack, out of an abundance of caution, some service members were transported from Al Asad Air Base, Iraq to Landstuhl Regional Medical Center in Germany, others were sent to Camp Arifjan, Kuwait, for follow-on screening.
"When deemed fit for duty, the service members are expected to return to Iraq following screening."
British forces are believed to have been present at Erbil - another Iraqi base targeted by Iran on the same night.
In a White House announcement the morning after the attacks, US President Donald Trump said: "The American people should be extremely grateful and happy no Americans were harmed in last night’s attack by the Iranian regime."
The attack on al-Asad Air Base was in retaliation for the assassination of Iran's top military commander, General Qassem Soleimani.
Tension between the West and Iran has spiked in the aftermath of the killing, with uncertainty over the 2015 nuclear deal - negotiated to prevent the Middle Eastern nation from obtaining a nuclear weapon.