JERUSALEM/BEIRUT, May 10 - Israel launched repeated rounds of rocket fire into Syria early on Thursday, Syrian state media reported, after Israel's military said Iranian forces in Syria had shelled one of its outposts near the border.The scale of Israeli rocket fire appeared to be far higher than in previous incidents and Damascus residents described seeing explosions above the city from air defense systems.Tensions between Israel and Iran have threatened to spill over in Syria, where the Iranian military and allied Shi'ite militia are backing Syrian President Bashar al-Assad in his war against rebels seeking to oust him."The Syrian air defenses are confronting a new wave of Israeli aggression rockets and downing them one after the other," state news agency SANA reported.Syrian state television was broadcasting footage of its air defenses firing at incoming rockets and playing patriotic songs.Israel's military spokesman Lieutenant Colonel Jonathan Conricus said Israel had retaliated for an attack on its outposts in the strategic Golan Heights plateau. He did not elaborate.Earlier, state news agency SANA and a war monitor, the Syrian Observatory for Human Rights, reported artillery fire from Israeli-held territory at Baath City in Quneitra province near the border. The Observatory said rockets were fired at military positions of the Syrian army and allied forces.The late-night incident followed a surge in tensions between Israel and Syria, where Iranian and Lebanese Hezbollah forces have been helping Damascus beat back a 7-year-old rebellion.Israel describes Iran as its biggest threat and Hezbollah as the biggest threat on its borders.Fearing that Iran and Hezbollah are setting up a Lebanese-Syrian front against it, Israel has occasionally struck at their forces. Iran blamed it for an April 9 air strike that killed seven of its military personnel in Syria, and vowed revenge.Conricus said that, in Thursday's attack, around 20 projectiles, most likely rockets, were fired by the Quds Force, an external arm of the Iranian Revolutionary Guards Corps, at around 12.10 a.m."A few of those rockets were intercepted" by Israel's Iron Dome air defense system, Conricus told reporters. "We are not aware of any casualties. The amount of damage that we currently assess is low."Asked if Israel retaliated for the salvo, he said, "We have retaliated but I have no further details about this."Expectations of a regional flare-up were stoked by U.S. President Donald Trump's announcement on Tuesday that he was withdrawing from the Iranian nuclear deal. Hours later, Israeli rockets targeted a military base in Kisweh, a commander in the pro-Syrian government regional alliance said.The strike killed 15 people, including eight Iranians, the Observatory said. Israel has neither confirmed or denied responsibility.