Several US and coalition personnel were wounded in a drone attack on Friday in Syria, a US official told Reuters, in the second major attack in recent days against US forces amid soaring tensions in the Middle East.
The US military initially assessed no casualties in the drone attack, but a more in-depth review found that some personnel had minor injuries including smoke inhalation and moved some to a different location.
The official, speaking on the condition of anonymity on Saturday, said none of the injuries were serious but some personnel were also being examined for traumatic brain injuries.
Several troops were moved to a different location for further evaluation, the official added.
No group has claimed responsibility for the attack, the official said, but similar attacks in the past have been carried out by Iran-backed groups.
The injuries from the drone attack followed a rocket strike by suspected Iran-backed militia on Monday that wounded five US personnel at Ain al-Asad airbase in western Iraq on Monday.
News of the latest injuries came as the Middle East as the region braces for a possible new wave of attacks by Iran and its allies.
Assassination of Hamas leader
Ismail Haniyeh, the political leader of Iran-backed Hamas, was assassinated in the Iranian capital Tehran on July 31, an attack that drew threats of revenge by Iran against Israel, which is fighting the Palestinian Islamist group in Gaza. Iran blamed Israel for the killing. Israel has not claimed responsibility.
The assassination and the killing of the senior military commander of the Iran-backed Lebanese group Hezbollah, Fuad Shukr, by Israel in a strike on Beirut, have fueled concern the conflict in Gaza was turning into a wider Middle East war.
Iran has said the US bears responsibility in the assassination of Haniyeh because of its support for Israel.
US Defense Secretary Lloyd Austin has said the United States would not tolerate attacks on US personnel but Washington was also trying to de-escalate tensions in the region.
Friday's attack took place at Rumalyn Landing Zone, which hosts US troops along with those from the US-led coalition.
The US has 900 troops in Syria and 2,500 in neighboring Iraq, who it says are on a mission to advise and assist local forces trying to prevent a resurgence of Islamic State, which in 2014 seized large swaths of both countries but was later pushed back.