Israel says it has struck almost all of Iran’s military infrastructure inside Syria in its biggest assault since the start of the civil war there.
The strikes came after 20 rockets were fired at Israeli military positions in the occupied Golan Heights overnight.
Syria’s military said the Israeli “aggression” had killed three people.
There was no immediate comment from Iran, whose deployment of troops to Syria to help President Bashar al-Assad has alarmed Israel.
Iran has repeatedly called for an end to the existence of the Jewish state.
Israel’s military had been anticipating an attack by Iranian forces after reportedly carrying out a number of strikes on their facilities in Syria in recent months. They included one on an airbase in April that killed seven Iranian troops.
What happened in the Golan?
The Golan Heights is a rocky plateau in south-western Syria, about 50km (30 miles) from the capital Damascus. Israel occupied most of the area in the 1967 Middle East war and later annexed it in a move not recognised internationally.
The Israel Defence Forces (IDF) said that early on Thursday morning 20 rockets had been launched at its forward posts there by the Quds Force, the overseas operations arm of Iran’s powerful Revolutionary Guards force.
IDF spokesman Lt Col Jonathan Conricus said four rockets were intercepted by the Israeli Iron Dome aerial defence system, while the others fell short of their targets. No injuries or damage were reported.
The Syrian Observatory for Human Rights, a UK-based group that monitors the civil war in Syria, confirmed that “dozens of rockets” were fired from Quneitra province and the south-western Damascus countryside towards the occupied Golan.
It did not identify those responsible, but said the rocket attack came after Israeli forces bombarded Baath, a town in the Golan demilitarised zone.
A senior source in an Iranian-led regional military alliance that supports Syria’s government also told AFP news agency that Israeli forces had fired first.