Israel's army said on Thursday it had hit dozens of Iranian military targets in Syria overnight after rocket fire towards its forces which it blamed on Iran, marking a sharp escalation between the two enemies.
The incident came after weeks of rising tensions and followed US President Donald Trump's decision to withdraw from the Iran nuclear deal on Tuesday, a move Israel had long advocated.
It was one of the largest Israeli military operations in recent years and its biggest such raid against Iranian targets, the military said.
Israel carried out the raids after it said around 20 rockets were fired from Syria at its forces in the occupied Golan Heights at around midnight.
It blamed the rocket fire on Iran's Al-Quds force, adding that Israel's anti-missile system intercepted four of the projectiles while the rest did not land in its territory.
If confirmed, the incident would be the first such rocket fire by Iranian forces in Syria towards Israel.
"We know that comes from the al-Quds force," army spokesperson lieutenant-colonel Jonathan Conricus said, referring to the special forces unit affiliated with Iran's Revolutionary Guard.
"The Israeli army takes very seriously this Iranian attack against Israel."
In the early hours of the morning, explosions were heard in Damascus, while live images were broadcast on television showing projectiles above the Syrian capital and several missiles destroyed by Syrian anti-aircraft systems.
Syrian state media reported that Israeli missile strikes hit military bases as well as an arms depot and a military radar installation, without specifying the location.
The official SANA news agency added that "dozens of missiles were shot down by anti-aircraft systems in Syrian airspace", saying a number of missiles had reached their targets.
Israel's military later confirmed it had carried out the raids, saying dozens of Iranian military targets had been struck and all of its aircraft had returned safely.
Conricus said intelligence, logistics, storage and vehicles as well as the origin of the rockets were targeted.
Syrian air defences that fired dozens of times on Israeli forces were also targeted, he said.
"We are not looking to escalate the situation," Conricus said, but warned Israel would respond forcefully if attacked.
An Israeli military statement said "this Iranian aggression is another proof of the intentions behind the establishment of the Iranian regime in Syria and the threat it poses to Israel and regional stability".
It added that it "will not allow the Iranian threat to establish itself in Syria. The Syrian regime will be held accountable for everything happening in its territory."
Israel has been warning for weeks that it will not accept Iran entrenching itself militarily in neighbouring Syria, where Tehran is supporting Syrian President Bashar al-Assad's regime in the country's seven-year civil war.
Israel has been blamed for a series of recent strikes inside Syria that have killed Iranians, though it did not acknowledge those raids.
It does acknowledge carrying out dozens of raids in Syria to stop what it says are advanced arms deliveries to Iran-backed Hezbollah, another key foe of Israel.
Israel had been preparing itself for weeks for possible Iranian retaliation.
Trump's withdrawal from the nuclear deal has added to tensions and led to a new level of uncertainty over how Iran will respond.
On Wednesday, Israeli Prime Minister Benjamin Netanyahu held talks in Moscow with Russian President Vladimir Putin, whose country has provided massive military and diplomatic backing to Assad's regime.
Netanyahu and Putin have held a series of meetings and telephone conversations in recent months, particularly regarding Syria.
The two countries have established a hotline to avoid accidental clashes in the war-torn country.
In February, Israel accused Iranian forces at the T-4 base in central Syria of sending a drone into Israeli territory.
After targeting Iranian units in Syria in retaliation, an Israel F-16 was shot down by Syrian anti-aircraft fire in one of the conflict's most notable escalations.
Israel then carried out what it called "large-scale" raids on Syrian air defence systems and Iranian targets, which reportedly included T-4.