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The US military on Wednesday reported that American troops experienced “minor injuries” from drone attacks in Iraq and Syria last week.
After a deadly Hamas attack on Israeli soil, Israel has retaliated with continuous strikes on Gaza, leading regional militias to consider attacks on those supporting Israel.
The US military has shot down several drones.
“Between October 17 and 18 [Eastern time], 21 US personnel received minor injuries due to drone attacks at Al Asad Airbase, Iraq and Al Tanf Garrison, Syria,” Pentagon spokesman Brig Gen Pat Ryder in a statement.
The members returned to duty after receiving care.
“It is important to note in some cases service members may report injuries such as TBI [traumatic brain injuries] several days after attacks occur, so numbers may change,” Brig Gen Ryder said.
US troops have been stationed on bases in Iraq and Syria as part of a global anti-ISIS mission since 2014.
President Joe Biden and US officials have warned of “significant escalation” against US personnel in the Middle East.
“We see a prospect for much more significant escalation against US forces and personnel in the near term,” a senior US defence official said this week.
An Iranian proxy group in Iraq on Tuesday said it would expand attacks on US bases in the region.
Mr Biden issued a warning to Iran's supreme leader Ayatollah Ali Khamenei after the threats.
“My warning to the Ayatollah was that if they continue to move against those troops, we will respond,” Mr Biden said.
Brig Gen Ryder said US Central Command will continue to provide updates on any further injuries.