Israel has launched air strikes against a Syrian airbase in the northern province of Latakia, according to media reports and officials.
A US official confirmed that "there was an Israeli strike" on Thursday but gave no detail on the location or the target, according to the AFP news agency.
Citing unnamed "exclusive sources", Saudi Arabian news network Al-Arabiya said on its website that "Israel was behind a series of explosions that rocked a Syrian airbase in the northern Latakia province.
"The bombing targeted a shipment of surface-to-air missiles [SAM] that was headed for Hezbollah in Lebanon," the report said.
Israel has 'no comment'
Al Jazeera's Stefanie Dekker, reporting from Jerusalem, said that Israel has refused to comment on the attack, but that attacks such as this are "not unusual", citing previous Israeli strikes on Syrian convoys near Damascus in January and May, as well as the destruction of a missile storage facility near Latakia in July.
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"People here are saying it is very possible that Israel could have carried out this air strike, but the official line from the Israeli army is 'no comment'," she said.
American broadcaster CNN cited an unnamed US administration official, who spoke on condition of anonymity, as saying Israeli warplanes carried out the attack, and that the target was missiles and related equipment the Israelis felt might be transferred to Hezbollah.
Former Syrian intelligence agent Afaq Ahmad, a defector now in exile in France, told Reuters news agency that contacts inside Syria told him that Russian-made ballistic missiles had been kept at the site that was attacked.
Israel struck a strategic missile battery near the village of Ain Shikak, he said, where President Bashar al-Assad's forces kept long-range Russian missiles that are among their most powerful weapons.
The Lebanese military said six Israeli jets had flown over Lebanese territory on Wednesday. Israeli aerial incursions over Lebanon are frequent, but such high numbers have in the past sometimes been an indication of military strikes against Syria.
Noting Syria's failure to retaliate after previous Israeli action, Ahmad said "Israel knows Assad has lost the ability to respond ... So it has been engaging in unannounced attacks on the weapons that could pose the most threat in the hands of Assad or if they are transferred to Hezbollah".