Israeli air strikes killed two Iranian-linked fighters in western Syria on Sunday, in Israel's third attack in the country since Thursday.
The early morning strike near the city of Homs followed attacks on Damascus on Thursday and Friday in which two members of Iran's Islamic Revolutionary Guard Corps were killed.
This comes amid heightened tensions, which also saw Israeli forces shoot down a drone that crossed over from Syria on Sunday.
The Syrian Observatory for Human Rights, a British-based war monitor, said “two pro-Iran fighters whose nationalities are so far unknown were killed” in the strikes targeting military positions of Syrian government forces and pro-Iran groups.
The monitor, which relies on a network of sources in Syria, said explosions rocked Homs and a fire broke out in a research centre.
“An arms depot belonging to Lebanese Hezbollah forces in the military airport of Dabaa, in the south-western sector of Homs, was destroyed,” Observatory head Rami Abdulrahman told AFP.
He said the two fighters had been killed in strikes on the arms depot.
State news agency Sana, citing a military source, said that “the Israeli enemy carried out an air assault … targeting positions in the city of Homs and its province”.
Sana reported that air defence forces intercepted several missiles but added that five soldiers were also wounded in the attack.
Then, Israel said it destroyed an unidentified drone late on Sunday night that they said crossed into its territory from Syria.
“Helicopters and fighter jets were deployed following an unidentified aircraft that seems to have crossed from the direction of Syria into Israeli territory,” the Israeli army said.
“The aircraft was downed in an open area,” it said. A spokesperson confirmed to AFP it was unmanned.
The incidents came shortly before Syrian state media said a car bombing rocked Damascus.
“An explosive device detonated in a civilian car, setting it alight without causing casualties,” Sana quoted police sources as saying.
The Interior Ministry said “two people were slightly injured” in the incident that targeted a pick-up truck.
It was not immediately clear who was responsible for the attack.
Iranian Foreign Ministry spokesman Nasser Kanani condemned the Israeli attacks in Syria, saying on Sunday that the “blood of these high-ranking martyrs will not go to waste” and that Tehran “reserves its right to respond … at the appropriate time and place”.
The Israeli strikes were the latest of hundreds it has conducted in Syria since the civil war started in 2011.
Most have targeted Iranian and Hezbollah positions, as well as advanced weapons transfers to Syrian forces.
The Lebanese Hezbollah militia was instrumental in the regime regaining most of Homs from the armed opposition in 2014 and 2015 and has maintained a presence in the area since.
Since an earthquake affected parts of Syria in early February, Israel has been increasingly attacking Iranian-linked targets in the country.
Syria constitutes the longest chunk of a supply route between Tehran and Hezbollah, Iran's most powerful Middle East ally.
On Thursday and Friday, Israeli raids on the outskirts of Damascus killed two members of Iran's Islamic Revolutionary Guard Corps, Iranian media said.
The Revolutionary Guard said one of its officers in Syria, identified as Milad Haydari, was killed in the Israeli attacks on Friday. Iranian media reported on Sunday the death of a second officer, Meqdad Meqdani.
A month before, Israeli strikes on Damascus and one of its suburbs killed two Syrian officers thought to have close links with the IRGC, according to sources in the regime and the opposition.
“Israel will continue its strikes. It appears to be receiving precise information,” said Syrian political commentator Ayman Abdel Nour Noor.
He said the strikes could help keep the perceived Iranian threat prominent in Israel, in case Israel chooses at some point to attack Iran directly to curb its nuclear programme.
The Israeli strikes came after an exchange of aerial attacks last month between US forces in Syria and pro-Iranian Shiite militias in eastern Syria.
Wael Alwan, director of information at the Jusoor research centre think tank in Istanbul, said the intensified Israel raids could be partly driven by suspicion that Iran has used earthquake aid flights to transfer more military supplies and technology to its militia allies in Syria.
“The recent Iranian provocation against US forces in the east has confused the picture,” Mr Alwan said. “But what is clear is that Israel feels the need to act to counter Iran's moves to strengthen its position in Syria after the earthquake.”
The conflict in Syria broke out in March 2011 following peaceful street demonstrations against five decades of Assad family rule.