Syrian state TV reports that Israeli warplanes bombed a military research site near Damascus in the early hours of Wednesday.
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The reports of the strike came after a day of unverified reports that Israeli forces had attacked a convoy on the Syrian border with Lebanon last night, following Israel's voicing of concerns that weapons from Syria may reach its enemies in Lebanon.
A Western diplomat and regional security sources told news wires that the convoy was attacked on Tuesday night.
The Lebanese army also reported a heavy presence of Israeli jets over its territory throughout the night. However a Lebanese security official said any attack did not take place on Lebanese territory.
Their target was a shipment of SA-17 anti-aircraft missiles, which target planes, and which sources said would be strategically "game-changing" in the hands of Hezbollah.
In the run-up to the reported strike, Israeli officials had issued public warnings about missiles reaching the Lebanese militant group Hezbollah, from Syria. Part of its new "Iron Dome" rocket defence system (pictured above) was also moved to the northern city of Haifa early this week - a move that officials said was routine - and Israel also echoed concerns from the US about Syria's presumed chemical weapons arsenal.
The four sources did not want to be named, due to the sensitivity of the situation, and information about what the vehicles may have been carrying, what forces were used or where precisely the attack happened has yet to be uncovered.
But they were adamant that the attack took place. "There was definitely a hit in the border area," one security source said. A Western diplomat in the region who asked about the strike said "something has happened", without elaborating. A Syrian activist also said that she had heard of a strike in southern Syria from opposition networks around the country, but could not confirm it.
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On Sunday Israeli Vice Premier Silvan Shalom said that Israel could be forced to intervene if there was any sign that chemical weapons would be used by either factions in Syria.
But Israeli sources also said that Syria's advanced "conventional" warfare weapons would represent as much of a threat to Israel as its chemical weapons if they fell into the hands of Israel's enemies.
Israel considers it "unacceptable" for the missiles to be in the hands of Hezbollah, as it would limit its ability to fly planes over Lebanon, Shashank Joshi, Research Fellow on Middle East for Rusi told Channel 4 News.
"It does explain why there was a flurry of cabinet meetings in Israel recently, which is unusual straight after the elections," said Mr Joshi. "Clearly they must have seen this missile system being moved. They could see something happening and decided to stop it."
When asked about any attack on Tuesday night, Mr Shalom would not confirm or deny it.
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Whether the strike took place within Syrian territory, or over the border in Lebanon, will affect how neighbouring countries respond.
Israeli jets regularly enter Lebanese airspace, but its forces have been more discreet about Syrian incursions.
A Lebanese security source denied any attack had happened within Lebanese territory to a Reuters reporter. However a strike on Syria could have big implications: Iran - Israel's arch-foe and one of Syrian President Assad's few allies - said on Saturday it would consider any attack on Syria as an attack on itself.
As yet there has been official statement on the reported strike. But it is in the interest of all the countries involved to deny, says Mr Joshi.
"Israel has no incentive to make a big deal out of this," he told Channel 4 News. "They have presumably achieved what they needed to. And Syrians don't want to make a big deal out of it and then be forced to retaliate."
11 November 2012
29 January 2013