BEIRUT, June 20: Russia has threatened aircraft from the U.S.-led coalition in Syrian-controlled airspace and suspended a hotline intended to avoid collisions in retaliation for the U.S. military shooting down a Syrian warplane.

The U.S. said it had downed the Syrian jet on Monday after it dropped bombs near the U.S.-backed Syrian Democratic Forces conducting operations against the Islamic State group, saying that was something it would not tolerate.

The downing of the warplane — the first time in the six-year conflict that the U.S. has shot down a Syrian jet — came amid another first: Iran fired several ballistic missiles Sunday night at IS positions in eastern Syria in what it said was a message to archrival Saudi Arabia and the United States.

The developments added to already-soaring regional tensions and reflect the intensifying rivalry among the major players in Syria's civil war that could spiral out of control just as the fight against the Islamic State group in its stronghold of Raqqa is gaining ground.

Meanwhile, Syrian opposition activists say a 48-hour truce in the southern city of Daraa has been extended.

The Britain-based Syrian Observatory for Human Rights says it was extended 24 hours. Daraa-based Ahmad al-Masalmeh confirmed the truce was extended Monday but did not know for how long.

The truce that went into effect Saturday came after some of the worst fighting in months between rebels and pro-government forces.

Activists say a "de-escalation agreement" brokered by Iran, Russia and Turkey in May has brought little relief. The agreement covers four zones in Syria where the rebels are fighting pro-government forces.

The Syrian government said the truce was part of national reconciliation efforts.

 
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