Coalition strike kills 18 allied fighters in Syria blunder — Pentagon

A U.S-led coalition airstrike against ISIS mistakenly killed 18 members of the Syrian Democratic Forces fighting President Bashar Assad, the Pentagon admitted Thursday.

It was not immediately clear if a U.S. plane was involved in the 'friendly fire' strike, which happened south of Tabqah in northern Syria on Tuesday.

"The strike was requested by the partnered forces, who had identified the target location as an ISIS fighting position," the Pentagon said in a statement.

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However, "the target location was actually a forward SDF fighting position," it said.

"The Coalition's deepest condolences go out to the members of the SDF and their families," it continued. "The Coalition is assessing the cause of the incident and will implement appropriate safeguards to prevent similar incidents in the future."

The SDF includes ethnic Assyrians, Turkmen, Armenians and Arabs but is dominated by Syria's main Kurdish fighting force, the People's Protection Units, or YPG.

Several nations have lent their air power to the coalition to defeat ISIS.