A senior Israeli official said that Russia’s decision to provide advanced S-300 anti-aircraft missile defense systems to Syria posed a serious challenge for the Jewish state. According to public broadcaster KAN, Syria has paid Russia a billion dollars for the anti-missile system, which will make it much more difficult for Israel to launch defensive air strikes against Iranian-linked targets in that country, as it has done over the last few years. The official added that Russia will receive this amount when the missiles are actually transferred to the Syrian regime. “The S-300 is a complex challenge for the State of Israel. We are dealing with the [decision] in different ways, not necessarily by preventing shipment [of the anti-aircraft system],” the official said. Prime Minister Benjamin Netanyahu told CNN that the move was “irresponsible” but said Israel was committed to continued deconfliction with Moscow in its military operations in the region. Notably, Russian officials withdrew plans to export an S-300PMU1 system to Syria in 2013, heeding a request from the Israeli government. Russian Defense Minister Sergei Shoigu said Moscow had in the past obliged Israel by refraining from providing Syria with the S-300. Russian Foreign Minister Sergey Lavrov, for his part, has confirmed that S-300 surface-to-air missile systems have begun arriving in Syria, adding a new layer of complexity to an already fraught situation in the region. The decision came less than a week after Syrian gunners using a less capable S-200 SAM battery inadvertently shot down a Russian reconnaissance aircraft while attempting to target Israeli F-16s. All 15 Russian crew members aboard the Il-20 died when the aircraft crashed in the Mediterranean Sea.