Israeli warplanes struck several targets in Syria early Friday, prompting retaliatory missiles 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 army denied any planes had been struck and the Syrian government has made similar unfounded claims in the past.
"(Our) aircraft was at no point compromised," army spokesman Peter Lerner said.
The Israeli 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 (army) aerial defence systems intercepted one of the missiles."
None of the missiles fired from Syria hit their targets, the army added.
One missile was intercepted north of Jerusalem by Israel's Arrow air defence system, Israeli media reported.
Both Israeli and foreign media have reported a number of Israeli air strikes inside Syria targeting arms convoys of Lebanese militant group 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 raid but may have been led to do so this time by the circumstances of the incident.
The missile fire prompted air raid sirens to go off in the Jordan Valley during the night, the Israeli army said.
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 Hezbollah.
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.
Iranian-backed Hezbollah has been fighting inside Syria in support of President Bashar al-Assad against the rebels.
While Israel has largely avoided getting sucked into the conflict directly, it has repeatedly struck Syrian territory, particularly targeting alleged Hezbollah weapons convoys.
Witnesses cited by the press also reported two explosions that could have been caused by the launch of the anti-missile system.
The Arrow 3 interceptor, designed to shoot down missiles above the atmosphere, was handed to air force bases in Israel in January after successful testing by Israel and the United States.
As well as hitting Hezbollah, Israel has also consistently targeted Syrian positions on the Golan Heights in response to alleged projectiles fired across the demarcation line between the countries.
In 1981 Israel annexed a large part of the Golan Heights which it seized from Syria in the 1967 Six Day War.
The annexation is still not recognised by the international community, which considers the territory Syrian.
Israel pays close attention to development in the Syrian conflict and the possibility that its arch-rival Iran will be able to install allies near the Israeli borders.
In the summer of 2006, Israel and Hezbollah fought a devastating war in Lebanon that killed nearly 1,200 Lebanese, mostly civilians, and about 160 Israelis, mostly troops.