The US has for the first time provided support to defend Syrian militants, trained by the US.
Pentagon spokesperson Capt Jeff Davis said "defensive support fire" was provided to the militants last Friday, while they were engaging suspected al-Nusra fighters.
The US-trained militants from the New Syria Force, were fighting alongside the Free Syrian Army.
Capt Davis said the US would provide defensive fire support to the NSF "no matter whom they came up against".
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