Israel's Defence Minister Moshe Ya'alon said Russia's intent to supply Syrian army with the advanced anti-aircraft systems is "a threat, as far as we're concerned," but asserted that the weapons have yet to be shipped out.
"I can't say there's been an acceleration (in weapons delivery)," Ha'aretz newspaper quoted him as saying. "The shipments haven't set out yet and I hope they won't. If they do arrive in Syria, God forbid, we'll know what to do."
Russia's Deputy Foreign Minister Sergei Ryabkov didn't say whether Russia has already shipped any of the long-range S-300 air defence missile systems, but added that Moscow isn't going to abandon the deal despite strong Western and Israeli criticism.
The missiles have a range of up to 200 kilometres and the ability to hit multiple targets simultaneously.
More From This Section
Ryabkov said the deal helps restrain some "hot heads" considering a military intervention in Syria.
Russia has been the key ally of President Bashar Assad's regime, protecting it from UN sanctions and providing it with weapons while the regime fights a battle of survival against rebels in a strife that has claimed over 70,000 lives in nearly two years.
Russia's foreign minister earlier this month said that Moscow had no new plans to sell the S-300 missiles to Syria but left open the possibility of delivering such systems under an existing contract.
Israel is concerned that the weapons meant for Syria's arsenal could fall into the hands of Hizbullah, which is fighting alongside Assad against the rebels in Syria.