Israel struck what it said were dozens of Iranian targets in Syria on Saturday after one of its jets was shot down by Syrian air defences and an Iranian drone launched from Syria entered its airspace.
The confrontation is considered the most serious between Israel and Iran since the start of the war in Syria in 2011. It also marks the first time that Israel has publicly acknowledged attacking Iranian targets in Syria.
"This is a serious Iranian attack on Israeli territory. Iran is dragging the region into an adventure in which it doesn't know how it will end," said Israel's chief military spokesman, Brig Gen Ronen Manelis. "Whoever is responsible for this incident is the one who will pay the price."
Israeli military spokesman Jonathan Conricus said that Syria and Iran were "playing with fire”, but stressed that his country was not seeking an escalation.
"This is the most blatant and severe Iranian violation of Israeli sovereignty in the last years," said Mr Conricus. "That's why our response is as severe as it is."
Earlier on Saturday, Israel said it intercepted an Iranian drone entering its airspace from Syria, labelling it an “attack". It responded by launching air strikes on what it said were the "Iranian control systems" that launched the drone — after which an F-16 Israeli jet crashed in northern Israel during heavy anti-aircraft counter fire from Syria. The Israeli pilots were reportedly alive, but one was severely injured.
Israel said its reprisals after the exchange were "large-scale" raids that attacked Syrian air defence systems and Iranian targets.
"Twelve targets, including three aerial defence batteries and four Iranian targets that are part of Iran's military establishment in Syria, were attacked," the military said.
Meanwhile, Hezbollah hailed Syrian air defences for shooting down the Israeli jet.
"This is the beginning of a new strategic era which puts an end to the violation of Syrian airspace and territory," said the Iran-sponsored Lebanese militant group, which is fighting in Syria on behalf of the Assad government.
Israel’s Ambassador to Moscow Harry Koren reiterated that all Iran-backed groups in Syria should immediately withdraw from the country’s southern de-escalation zone.
"We prefer to talk about the implementation of different agreements on the zones of de-escalation, in our case, in the south on the border with Israel,” he was quoted as saying by Russia’s Interfax news agency.
"Specifically, any presence of Iranian units, Hezbollah and Shiite rebels should immediately be curtailed."
The deputy head of Iran’s elite Revolutionary Guards Corps declined to comment on the issue, the semi-official Tasnim news agency reported.
"We cannot confirm this report on the drone because Israelis are liars … if Syrians confirm it, Iran will confirm it as well," Brig Gen Hossein Salami said.
A pro-Damascus regime military alliance — which includes Iran and its Lebanese proxy, Hezbollah — said any new act of “terrorism” by Israel will be met with a “severe and serious response”.
An alliance statement said reports the drone entered Israeli airspace were “a lie”, and that the drones are used to combat ISIL.
But Mr Conricus said it was intercepted well inside Israeli territory over the city of Beit Shean, near the Jordanian border.
He did not say whether the drone was armed or strictly for reconnaissance, but said: "We know it was on a military mission sent by Iranian military forces."
Israeli aircraft then "targeted the Iranian control systems in Syria that sent the UAV into Israeli airspace," according to Mr Conricus.
The aircraft met "massive Syrian anti-air fire," Mr Conricus said, and the F-16 crashed afterwards in the Jezreel valley in northern Israel.
According to a separate military statement, "multiple anti-aircraft missiles were fired at IAF [Israel Air Force] aircraft."
"The pilots of one of the aircraft abandoned as per procedure. The pilots landed in Israeli territory and were taken to the hospital for medical treatment."
Mr Conricus said the army had confirmed "accurate hits of [the] Iranian UAV control facility" in Syria.
"Iran is responsible for this severe violation of Israeli sovereignty," Mr Conricus said on Twitter.
Meanwhile, Syrian state TV quoted a military source as saying that air defences responded to Israeli “aggression” against a military base.
"The Israeli enemy entity at dawn today conducted a new aggression against one of the military bases in the central region. Our air defences confronted it and hit more than one plane," the source said.
According to the Britain-based Syrian Observatory for Human Rights, which has been monitoring the war, the Israeli raids that followed the alleged drone interception targeted a number of military bases in the east of the central Syrian province of Homs.
The bases are used by both Iranian and Russian military personnel deployed in support of Syrian president Bashar Al Assad’s regime, it added.
Syrian state media said the later raids targeted military positions in the south of the country.
Air raid sirens had gone off in Israel in the early hours of the morning following the UAV interception and raids.
The Israeli army said it was "monitoring events and is fully prepared for further action, depending on assessments and necessity”.