Israeli forces unleashed a heavy bombardment against Iranian military installations in Syria on Thursday in what Israel called retaliation for an Iranian rocket barrage on its positions in the occupied Golan Heights, the most serious military confrontation between the two bitter enemies to date.
The two rivals have long fought each other through proxies, and with the new exchange each seemed to be sending a warning that a direct clash between them could swiftly escalate.
"If we get rain, they'll get a flood," Israeli Defense Minister Avigdor Lieberman warned.
The scope of the attacks — which Israel called its largest in Syria since the 1973 Mideast war — raised the specter of a full-fledged war between Iran and Israel in Syria, a conflict that could potentially drag the militant Hezbollah and Lebanon into the mix with devastating effects, although both sides appeared to signal they wanted the confrontation to remain contained, at least for now.
Israel, however, has been emboldened by President Donald Trump's withdrawal from the Iran nuclear deal earlier this week, and the latest escalation seemed to signal a potentially coordinated surge in military activity targeting Iran.
The Israeli military said Thursday it hit nearly all of Iran's military installations in Syria in response to the overnight Iranian rocket barrage that targeted Israeli front-line military positions in the Golan Heights, a strategic plateau that Israel captured in the 1967 Middle East war. It was the first time Israel has directly accused Iran of firing toward Israeli territory.
Iranian media described the Israeli attack as "unprecedented," but there was no official Iranian comment on Israel's claims.
Iran has vowed to retaliate for repeated Israeli airstrikes targeting its forces in Syria. But it seemed to carefully calibrate its response by targeting the Golan Heights, which Israel annexed in 1981 in a move that is not internationally recognized, instead of striking Israel proper.
Tehran is wary of a wider military conflagration with Israel that could jeopardize its military achievements in Syria at a time when it is trying to salvage the international nuclear deal and may be limited in its ability to strike back.
The recent clashes reveal the difficulty both sides face in dealing with an unprecedented situation, said Jean-Pierre Filiu, a professor of Middle East studies at Sciences Po, Paris School of International Affairs.
The clashes will eventually likely lead not to further escalation, but to the "consolidation of new 'red lines' tacitly endorsed by Israel and Iran," he said in an analysis written for the Carnegie Middle East Center.
The extent of the damage inflicted by the Israeli airstrikes was not immediately clear.
Israel said among the targets were weapons storage, logistics sites and intelligence centers used by elite Iranian forces in Syria. It also said it destroyed several Syrian air-defense systems after coming under heavy fire and that none of its warplanes were hit.
The Syrian military acknowledged that the strikes destroyed a radar station and an ammunition warehouse, and damaged a number of air defense units. It said three people were killed and two were wounded.
The Britain-based Syrian Observatory for Human Rights, which closely monitors the civil war through sources inside Syria, said 23 fighters, including five Syrian soldiers, were killed. It was not immediately clear if any Iranians were among the dead.
The White House swiftly condemned Iran's "provocative rocket attacks from Syria against Israeli citizens" and expressed strong support for "Israel's right to act in self-defense," while Russia said the Israeli strikes marked a dangerous escalation and urged both Israel and Iran to avoid provoking each other.
In a statement, White House press secretary Sarah Huckabee Sanders said "the Iranian regime's deployment into Syria of offensive rocket and missile systems aimed at Israel is an unacceptable and highly dangerous development for the entire Middle East."
Israel has carried out over 100 airstrikes in neighboring Syria since the civil war erupted in 2011, most believed to be aimed at suspected Iranian weapons shipments bound for the Hezbollah militant group.
But in the past few weeks, Israel has shifted to a more direct and public confrontation with Iran, striking at Iranian bases, weapons depots and rocket launchers across Syria, and killing Iranian troops. Israel accuses Tehran of seeking to establish a foothold on its doorstep, something it has vowed never to allow.
Reflecting the scope of the pre-dawn attack, Russia's military said 28 Israeli jets were involved, striking Iranian and government sites in Syria with 70 missiles. It said half the missiles were shot down.
Speaking at the Herzliya Conference, an annual security gathering north of Tel Aviv, Lieberman said Israel would respond fiercely to any further Iranian actions.
"We will not let Iran turn Syria into a forward base against Israel," the Israeli defense minister said. "If we get rain, they'll get a flood. I hope that we ended this chapter and that everyone understood."
In a statement issued as Israel's security cabinet met, Israeli Prime Minister Benjamin Netanyahu said the strike sent a "clear message" that "whoever attacks us — we will attack them sevenfold and whoever prepares to attack us — we will act against them first."
Iranian state television announced the Israeli strikes, sourcing the information to Syria's state-run SANA news agency, and described the Israeli attack as "unprecedented."
Israel captured the Golan Heights in the 1967 war and annexed it in 1981. In 1974, Israel and Syria reached a cease-fire and a disengagement deal that froze the conflict lines with the plateau in Israeli hands.
Damascus shook with sounds of explosions just before dawn, and firing by Syrian air defenses over the city was heard for more than five hours.
Russian Foreign Minister Sergey Lavrov said Moscow sees Thursday's strikes as a "very alarming development."
He noted that in contacts with the leadership of both countries, including a meeting Wednesday between Netanyahu and Russian President Vladimir Putin in Moscow, "we underlined the necessity of avoiding any actions that might be mutually provocative."
Russia sent forces to Syria to back President Bashar Assad in 2015. But Israel and Russia have maintained close communications to prevent their air forces from coming into conflict. The pan-Arab Al Hayat newspaper reported Thursday that Russia and Israel were developing an agreement to keep Iran out of southern Syria and allow Syrian government forces to retake the region.
Israel said early Thursday that Iran's Quds Force fired 20 rockets at Israeli front-line military positions in the Golan Heights. Lt. Col. Jonathan Conricus, a military spokesman, said four of the rockets were intercepted, while the others fell short of their targets. The incoming attack set off air raid sirens in the Golan.
Conricus said Israel was not looking to escalate the situation but that troops will continue to be on "very high alert."
"Should there be another Iranian attack, we will be prepared for it," he said.
The two sides have been on a collision course for months.
In February, Israel shot down what it said was an armed Iranian drone that entered Israeli airspace. Israel responded by attacking anti-aircraft positions in Syria, and an Israeli warplane was shot down during the battle.
Earlier this week, Syrian state media said Israel struck a military outpost near Damascus. The Observatory said the missiles targeted depots and rocket launchers that likely belonged to Iran's elite Revolutionary Guard, killing at least 15 people, including eight Iranians.
Last month, an attack on Syria's T4 air base in the central Homs province killed seven Iranian military personnel.