US drones 'once again harassed' by Russian fighter jets over Syria

US military drones over Syria were "harassed" three days in a row by Russian fighter jets, the US military has said.

In a statement, the US said that the third encounter – on Friday – lasted for about two hours during which three MQ-9 drones were "once again harassed" by Russian fighter aircraft while flying over Syria.

The first conflict occurred last Wednesday when Russian fighter aircraft "engaged in unsafe and unprofessional behaviour", when three US MQ-9 drones were monitoring so-called Islamic State (IS) targets.

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On the most recent incident, Lieutenant General Alex Grynkewich, Head of US Air Forces Central Command, said in a statement: "Russian aircraft flew 18 unprofessional close passes that caused the MQ-9s to react to avoid unsafe situations."

Footage has shown Russian military SU-34 and SU-35 aircraft employing flares in the flight path of a US MQ-9 aircraft on 6 July over Syria.

The US Department of Defense said: "Russian forces have displayed increasingly unprofessional and unsafe actions while operating in Syria, threatening the safety of both US and Russian forces."

Both the US and Russia are operating in Syria – the US as part of the anti-IS coalition, whereas Russia is operating in support of Syrian President Bashar al-Assad.