Beirut, May 10, 2018 (News Wires) - Iranian forces in Syria launched a rocket attack on Israeli army bases in the Golan Heights early on Thursday, Israel said, prompting one of the heaviest Israeli barrages in Syria since the conflict there began in 2011. The attack on the Israeli-occupied Golan Heights, just past midnight, marked the first time Iranian forces have hit Israel from Syria, where they have deployed along with Iran-backed Shiite militias and Russian troops to support President Bashar Assad in the seven-year-old civil war. Israel said the Iranian salvo of 20 Grad and Fajr rockets were shot down by its Iron Dome air defence system or fell short of the Golan targets. The Quds Force, an external arm of Iran's Revolutionary Guards, carried out the launch, Israel said. "It was commanded and ordered by (Quds Force chief General) Qassem Soleimani and its has not achieved its purpose," military spokesman Lieutenant-Colonel Jonathan Conricus told reporters. Israel struck back by destroying dozens of Iranian military sites in Syria, Conricus said, as well as Syrian anti-aircraft units that tried unsuccessfully to shoot down Israeli planes. "We do not know yet the (Iranian) casualty count," he said. "But I can say that in terms of our purpose, we focussed less on personnel and more on capabilities and hardware ... to inflict long-term damage on the Iranian military establishment in Syria. We assess it will take substantial time to replenish." Syrian state media said dozens of Israeli missile strikes hit a radar station, Syrian air defence positions and an ammunition dump, underscoring the risks of a wider escalation involving Iran and its regional allies. Tensions between Israel and Iran had already spilled over in Syria, worrying Russia, which want to stabilise Assad's rule. Iran vowed retaliation after a suspected Israeli air strike last month killed seven of its military personnel in a Syrian air base. Israel regards Iran as its biggest threat, and has repeatedly targeted Iranian forces and allied militia in Syria.