Israel says it has hit dozens of targets in Syria belonging to the government and allied Iranian forces.
The Israeli military says the "wide-scale strikes" responded to rockets fired by an Iranian unit into Israel.
Syria says two civilians died and that Syrian air defences shot down most of the missiles over Damascus. Other reports say the death toll was higher.
Local reports said loud explosions were heard in the capital. Pictures on social media showed a number of fires.
On Tuesday morning, the Israeli military said it had intercepted four rockets fired from Syria towards northern Israel. It said the rockets did not hit the ground.
Israel has carried out hundreds of strikes in Syria since the civil war broke out there in 2011 in an attempt to thwart what it calls Iran's "military entrenchment" there and shipments of Iranian weapons to Lebanon's Hezbollah movement.
What did Israel say?
#BREAKING: We just carried out wide-scale strikes of Iranian Quds Force & Syrian Armed Forces targets in Syria in response to the rockets fired at Israel by an Iranian force in Syria last night.
— Israel Defense Forces (@IDF) November 20, 2019
End of Twitter post by @IDF
"During our strike of Iranian & Syrian terror targets, a Syrian air defence missile was fired despite clear warnings to refrain from such fire. As a result, a number of Syrian aerial defence batteries were destroyed," the IDF said.
The IDF also said it held "the Syrian regime responsible for the actions that take place in Syrian territory and warn them against allowing further attacks against Israel".
Iran's Quds Force, which answers directly to Iran's Supreme Leader, Ayatollah Ali Khamanei, is the external operations wing of the Islamic Revolution Guard Corps (IRGC).
Israel did not target the Russian-made advanced S-300 surface-to-air missile systems deployed near the positions of Russian troops, Israeli media report.
Russia, whose forces have helped turned the tide of Syria's civil warRead More – Source