JERUSALEM — Israel made the unusual move Monday of announcing a strike on Iran-linked forces in Syria after a rocket attack, as it enters into an increasingly open confrontation with its arch foe that is also increasing friction with Moscow.

The strikes, which hit targets that included a training camp, munitions storage depots and a site at Damascus International Airport, were reported by Russia to have killed at least four Syrian servicemen. They came after a day of escalation in Syria on Sunday. 

Damascus and Moscow had accused Israel of carrying out a rare daylight air raid in Syria on Sunday morning, after which Israel said a rocket was fired at its territory by Iranian forces in the country at around 3 p.m. 

It marked the second time during Syria’s civil war that Israel has accused Iranian forces of launching rockets from the country, where Tehran has sent troops to back President Bashar al-
Assad. Israel carried out a wave of attacks on Iran-linked targets in Syria in May after a volley of Iranian rockets, which also followed reports of earlier Israeli fire.  

Analysts said Sunday’s launch of what the Israeli military said was a midrange surface-to-
surface missile may have been an attempt by Iran to establish a level of deterrence against Israel, which has repeatedly bombed its military assets in the country.  

Israel sees the presence of Iran-linked forces in Syria as a red line and has vowed to use air power to prevent Iranian entrenchment, which it says is an attempt to establish a long-term vanguard against Israel rather than to win back Syria for Assad.

But the continued Israeli strikes have irked Moscow, which also has troops at Syrian bases backing Assad. 

Although Israel said it had used the usual “deconfliction” channels with Russia, Moscow said Monday that its “patience is limited” with Israel and that it would consider supplying additional weapons to Syria if such strikes continued.

“Israel used to strike military targets in Syrian territory, but now it’s targeting Damascus International Airport,” Andrei Krasov, deputy chairman of the Russian parliament’s defense committee, told the Interfax news agency. “Israel has flagrantly breached international law. This is an act of aggression against a sovereign state.” 

Last year, Russia began delivery of advanced S-300 air defenses to Syria despite Israeli protests, after a Russian plane was downed by Syrian antiaircraft fire during an Israeli raid. 

Israel had pinned its hopes on Russia to secure guarantees that Iranian-linked troops are not present in areas near its border. 

Lt. Col. Jonathan Conricus, a spokesman for the Israel Defense Forces, said Sunday’s rocket was fired from an area around Damascus where Israel had “received assurances” that there were no Iranian forces.

Skiers on Mount Hermon, on the Israeli-occupied Golan Heights, caught footage of the Iron Dome system intercepting the missile earlier in the day. The slopes were closed Monday. 

“We will not ignore such acts of aggression as Iran attempts to entrench itself militarily in Syria,” Israeli Prime Minister Benjamin Netanyahu said Monday. “We are acting against Iran and against the Syrian forces that abet the Iranian aggression. Whoever tries to hurt us — we hurt them.” 

Israel’s response came overnight, with the military making an announcement as its jets took off in the early hours of Monday.

“The IDF is currently striking Iranian Quds targets in Syrian territory,” it said in a statement, referring to the elite branch of Iran’s Revolutionary Guard Corps. “The IDF warns the Syrian Armed Forces against attempting to harm Israeli territory or forces.”

Conricus, the spokesman, said that the targets had included Iran’s main logistics hub at Damascus International Airport, where secondary explosions were recorded after the hit. 

Syria’s national news agency, SANA, posted videos of huge explosions lighting up the night sky. In a video posted on Facebook, filmed from Damascus University, students can be heard cheering loudly as the air defenses open fire.

Syria said it had launched a “heroic response” to the wave of strikes early Monday, downing most of the “hostile missiles.”

Conricus said that Syrian air defenses had been targeted only after they fired on the Israeli jets. 

Lebanon’s Al Mayadeen website quoted its correspondent in Damascus as saying that the strikes were concentrated in Kisweh, which is the site of an alleged Iranian base that Israel has struck before, and in the southwestern province of Quneitra.

Netanyahu took the unusual step last month of confirming another strike in Syria, admitting that Israel had struck “hundreds” of targets in the country in recent years, in an apparent relaxing of its previous policy of largely not confirming or denying raids. 

Still, the military would not comment on whether Israel had carried out the strike near Damascus on Sunday morning that preceded the rocket launch.

Syria’s state news agency said that the earlier Israeli strike Sunday morning was “confronted” and prevented from “achieving any of its objectives.” 

Russia’s National Defense Control Center said Syria’s air defenses shot down seven missiles targeting an airport southeast of ­Damascus. 

Liz Sly in Beirut and Amie Ferris-Rotman in Moscow contributed to
this report.