Israel claims it struck almost all of Iran's military capabilities in Syria after what it says was an Iranian missile attack on the Golan Heights.
In the most direct confrontation between Israel and Iran to date, the regional enemies exchanged fire for hours late Wednesday.
The extended barrage of fire comes amid soaring tensions between Israel and Iran, rivals battling for regional influence, and less than two days after the United States withdrew from the deal to curb Iran's nuclear program.
In a YouTube statement Thursday, Israeli Prime Minister Benjamin Netanyahu said Iran had "crossed a red line," and that Israel's action was appropriate.
Netanyahu spoke with British Prime Minister Theresa May on the phone on Thursday evening. According to a readout of the call from the Israeli Prime Minister's Office, the two spoke about "Iranian aggression, developments in the region, and the situation in Syria."
Netanyahu thanked May for condemning Iran and affirming Israel's right to defend itself.
"Whoever hits us will get hit seven times over. Whoever prepares themselves to attack us will be attacked first. That is what we have done and that is what we will continue doing," Netanyahu said.
According to the UK government's readout of the conversation, May called for "calm on all sides." The sentiment was echoed by the European Union, which released a statement urging "all regional actors to show restraint and avoid any escalation, which could further undermine regional stability."
Israel said more than 20 rockets were launched by Iranian forces in Syria in the direction of Israel late Wednesday, often criss-crossing in the clear night skies. A number of those rockets were intercepted by Israel's Iron Dome aerial defense system, resulting in bright and sudden explosions.
Israel retaliated with what appeared to be surface-to-surface missiles, and Syrian anti-aircraft batteries hosed the sky with fire in an effort to intercept them. Thunderclaps of Israeli artillery fire reverberated across the frontier between Syria and Israel, with the faint sound of impact echoing back moments later.
"Israel has hit almost all of Iran's infrastructure in Syria," Defense Minister Avigdor Liberman said. "If it will rain in Israel, there will be a biblical flood on the other side."
He reiterated Israel's stance that this latest offensive was not an ongoing operation, adding: "I hope this chapter is over, and everyone understands the situation, and we won't have to spend nights in situation rooms."
Lt. Col. Jonathan Conricus said Israel had successfully hit dozens of Iranian targets in Syria in what he described as "the largest operation against Iranian targets" in years.
Iran's leaders have not yet issued a response to the Israeli accusations or the military strikes, but if confirmed it would be the first time Iranian forces have fired rockets directly at Israeli forces.
All night, drones buzzed overhead, heard but not seen in the darkness.
Three people were killed and two others were injured by the Israeli missiles, the Syrian military said in a statement. The strikes also destroyed a radar station, ammunition depot and caused material damage to Syria's air defense, it said.
The Syrian military claimed that its air defense managed to intercept and destroy a "big part of the wave of Israeli missiles that targeted a number of our military positions."
In a statement delivered early Thursday, a spokesman for the Israel Defense Forces pinned the blame for the rocket fire on the Quds Force, an elite division of Iran's Revolutionary Guard Corps, which has forces in Syria and is often seen as the face of Iran's regional ambitions.
Conricus said the rockets, which were targeted at front-line Israeli military positions in the Golan Heights, were all either downed by aerial defense systems or fell short and landed in Syria.
On Wednesday night, state-run Sana TV, in southern Syria, carried reports that Israel had fired several missiles at the city of Baath in Quneitra, none of which resulted in casualties.
A short time later, Syrian state-run media reported that while dozens of "hostile" Israeli missiles had been intercepted in Syrian airspace, at least two others had hit an ammunition depot and destroyed a radar site.
The targets included rocket launchers, intelligence posts, military command posts, and weapons depots. No Israeli fighter jets were hit in the strikes, but Conricus said they came under heavy anti-aircraft fire. He added that "ground assets were also used to strike into Syria." The IDF released a map showing a list of targets it said it hit.
Russia, which like Iran has intervened in Syria's war on the side of the government, called for "restraint on all sides."
In a statement, the White House said: "The United States condemns the Iranian regime's provocative rocket attacks from Syria against Israeli citizens, and we strongly support Israel's right to act in self-defense."
"Iran's Islamic Revolutionary Guard Corps (IRGC) bears full responsibility for the consequences of its reckless actions," the statement added.
Israel had been expecting an Iranian response for some time, following a series of military strikes in Syria that targeted Iranian positions. Syria and Iran blamed those strikes on Israel, and Iran's leaders vowed revenge.
One of the strikes occurred Tuesday night, only hours after President Donald Trump had withdrawn the United States from the Iran nuclear deal, sparking fears of further destabilization in the Middle East.
A US defense official told CNN that it was an Israeli military strike that hit suspected Iranian weapons near Damascus. Israel has not commented on the strike.
On Tuesday, the IDF went on high alert in anticipation of an Iranian response, in addition to calling up a limited number of reserve troops "on an as needed basis." Israel opened bomb shelters in the Golan Heights, but did not instruct people to enter the shelters.
On Wednesday morning, the IDF chief of staff, Lt. Gen. Gadi Eisenkot, visited the Golan Heights to meet with military and civilian leaders on the IDF's assessment of the situation.
Israel says it has a series of "red lines" in Syria; among them, preventing Iran's military entrenchment in the country. Netanyahu reiterated that in his statement Thursday, calling on the international community to prevent Iran's Quds Force from basing in Syria. "We need to unite to dismember the arm of the evil that is spreading itself in every place," he said.
Netanyahu also said Israel's most recent strike was a message to the Assad regime.
He said Israel's "operations are against Iranian targets in Syria, but if the Syrian army will act against us, we will act against them."
"That is exactly what happened yesterday. [The] Syrian army fired ground-to-air missiles against, us so we hit them."
Putin had urged restraint
On Wednesday, Netanyahu met Russian President Vladimir Putin in Moscow on Victory Day, which marks the 1945 defeat of Nazi Germany.
In a bilateral meeting after the celebrations, Netanyahu said that Israel has the "obligation and right to defend itself against Iranian aggression, from Syrian territory. They are trying to transfer forces and deadly weapons there with the explicit goal of attacking the State of Israel. Certainly, it is Israel's right to take such steps as necessary to defend itself against this aggression."
Putin, as one of the few leaders who has good relations and significant influence with both Israel and Iran, urged restraint.
"The situation, unfortunately, is very acute. I want to hope that we will be able not only to discuss with you, but also to look for solutions that would soften the situation," said Putin.
Russia and Israel coordinate their actions within Syria for the purpose of deconfliction. According to Conricus, Israel notified Russia before carrying out the overnight strikes.
Russian and Iranian intervention in Syria's long-running civil war helped tilt the balance of power back toward Syrian President Bashar al-Assad.
In an interview with the Greek newspaper Kathimerini, Assad said fears of a third world war erupting in Syria were misplaced, despite escalating tensions.
Assad told the paper that "wise Russian leadership" would prevent such an event, describing the current conflict as "something more than a cold war, less than a full-blown war." He also took aim at the US, saying the Russians "know that the agenda of the deep state in the United States is to create a conflict."
Israel annexed the Golan Heights in 1981 after capturing it from Syria in the Six Day War in 1967. The international community has never recognized the annexation and regards the Golan Heights as Israeli-occupied territory.