Israeli warplanes struck several targets in Syria early Friday, prompting retaliatory missile launches, in the most serious incident between the two countries since the Syrian civil war began six years ago.
Syria's military said it had downed an Israeli plane and hit another as they were carrying out pre-dawn strikes near the famed desert city of Palmyra that it recaptured from jihadists this month.
"Our air defence engaged them and shot down one warplane over occupied territory, hit another one, and forced the rest to flee," the army said in a statement carried by state news agency SANA.
The Israeli military denied that any planes had been struck. The Syrian government has made similar unfounded claims in the past.
"The safety of Israeli civilians or the Israeli air force aircraft was at no point compromised," Israeli army spokesman Peter Lerner told AFP.
Nevertheless, analysts said the incident represented a significant shift in Syria's response to Israeli airstrikes inside its territory.
The air force said earlier that it had carried out several strikes on Syria overnight, but that none of the ground-to-air missiles fired by Syrian forces in response had hit Israeli aircraft.
It was an unusual confirmation by the Jewish state of air raids inside Syria.
"Overnight... aircraft targeted several targets in Syria," an Israeli army statement said.
"Several anti-aircraft missiles were launched from Syria following the mission and (Israeli) aerial defence systems intercepted one of the missiles," it said.
None of the missiles fired from Syria hit their targets, the army added.
One missile was intercepted by Israel's Arrow air defence system, Israeli media reported.
It would be one of the first times the system has been used.
A Jordanian military source said shrapnel from one missile fell in the north of the kingdom without causing any casualties.
- 'Significant shift' -
In April 2016, Prime Minister Benjamin Netanyahu admitted for the first time that Israel had attacked dozens of convoys transporting weapons in Syria destined for Lebanon's Hezbollah, which fought a devastating 2006 war with Israel and is now fighting alongside the Damascus regime.
The Jewish state does not usually confirm or deny each individual raid but may have been led to do so this time by the circumstances of the incident.
The missile fire from Syria prompted air raid sirens to go off in the Jordan Valley during the night, the Israeli army said.
Israel and Syria are still technically at war, though the border had remained largely quiet for decades until 2011 when the Syrian conflict broke out.
Assaf Orion, senior research fellow at Israel's Institute for National Security Studies, said Syria's response was a "significant" shift.
Until now, he said, when Israel attacked Hezbollah convoys in the country, it "usually went without a response or with an insignificant response from the Syrian side."
"(With this attack) the Syrian regime is trying to tell Israel it can't stand it anymore and those actions will not be free of charge."
President Bashar al-Assad's position has been strengthened in recent months with his forces reclaiming the whole of Syria's second city Aleppo, as well as enjoying continuing Russian support.
Orion said the Syrian leader was feeling emboldened.
"Assad is not feeling he is looking down a gun barrel so his future is now more guaranteed than it was in the past."
"He is saying: 'Don’t push me. I am not as weak as I used to be.'"
Yaakov Amidror, a former head of Israel’s National Security Council, said weapons convoys of the Iran-backed Hezbollah remained a "red line" for the Jewish state and that Israel would continue to attack them when deemed necessary.
Witnesses cited by the Israeli press reported two explosions that could have been caused by the launch of the anti-missile system.
The Arrow 3 interceptor, designed to shoot down ballistic missiles, was handed to Israeli air force ground crews in January after successful testing by Israel and the United States.
Israel seized most of the Golan Heights from Syria in the 1967 Six-Day War and annexed it in 1981, in a move never recognised by the international community.
Israel pays close attention to developments in the Syrian conflict for fear that it could be exploited by its arch-rival Iran to install allies close to the armistice line on the Golan and Israel's borders.