Israeli warplanes attacked a shipment of Russian missiles inside a Syrian government stronghold that were destined for the Lebanese militant group Hezbollah, U.S. officials have said.
One security source said the attack occurred late on Wednesday night in the Syrian port city of Latakia and that the targets were Russian-made SA-125 missiles.
Another Obama administration official confirmed the airstrike, but provided no details. There was no immediate confirmation from Syria.
Latakia is a stronghold of Syrian President Bashar al-Assad, an important port city where the Alawite community to which he belongs is concentrated.
Syrian activists and opposition groups reported large explosions on Wednesday night that appeared to come from inside an air defence facility in Latakia. They said the cause of the blasts was not known.
Since the civil war in Syria began in March 2011, Israel has carefully avoided taking sides, but has struck shipments of missiles inside Syria at least twice this year.
The Syrian military, overstretched by the civil war, has not retaliated, and it was not clear whether the embattled Syrian leader would choose to take action this time.
Assad may decide to again let the Israeli attack slide, particularly when his army has the upper hand on the battlefield inside Syria.