A top US commander has warned Russia that the United States ‘will defend itself if threatened’ after warplanes attacked near American forces operating in Syria.

Lt. Gen. Stephen Townsend, based in Baghdad, vowed to defend US special operations forces in northern Syria if they come under another attack.

‘We’ve informed the Russians where we’re at,’ he told CNN. ‘(They) tell us they’ve informed the Syrians, and I’d just say that we will defend ourselves if we feel threatened.’

The warning follows what defense officials described as an ‘unusual’ incident Thursday when President Bashar al-Assad’s regime deployed warplanes to attack an area near where US special operations forces were operating.