A US-led coalition fighter jet has shot down a Syrian military plane in Raqqa province, the US has confirmed.
The SU-22 fighter bomber was engaged by an F/A-18E Super Hornet after it had dropped bombs near the US-backed Syrian Democratic Forces, the Pentagon said.
It is the first time in the Syrian conflict that the US-led coalition has shot down a Syrian jet.
Syria condemned what it called a “flagrant attack” that would have “dangerous repercussions”.
In a separate incident, Iran’s Revolutionary Guards said they had launched several missiles from Iran into eastern Syria on Sunday, targeting IS fighters.
The SU-22 incident took place on Sunday afternoon near the town of Tabqa, where the Syrian Democratic Forces (SDF) have been fighting Islamic State militants as part of a drive to retake the city of Raqqa, the IS stronghold further to the east.
It is believed to be the first air-to-air kill of a manned aircraft by a US military jet since the Kosovo campaign in 1999.
The Pentagon said that pro-government militiamen had attacked SDF units, driving them from the town of Ja’Din.
The pro-government forces are not fighting the battle for Raqqa, but they have been making ground against IS in the surrounding area, south-west of the city.
The US-led coalition conducted what the Pentagon said was a “show of force” – a reported buzzing of the pro-government troops by jets – to stop the attack and then called the Syrian government’s ally, Russia, to try to “de-escalate the situation and stop the firing”.
However, the SU-22 dropped bombs on SDF positions a few hours later, the Pentagon said, and “in accordance with rules of engagement and in collective self-defence of Coalition-partnered forces [the plane] was immediately shot down”.
Attempts to warn the plane away using an emergency radio frequency failed, the US Central Command said.
The Pentagon statement added: “The demonstrated hostile intent and actions of pro-regime forces toward Coalition and partner forces in Syria conducting legitimate counter-Isis (IS) operations will not be tolerated.”
The Pentagon statement said the coalition did “not seek to fight the Syrian regime, Russian or pro-regime forces partnered with them, but will not hesitate to defend coalition or partner forces from any threat”.