– Israel made the unusual move Monday of announcing a strike on Iranian-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 including a training camp, munitions storage depots and a site at the Damascus International Airport and were reported by Russia to have killed at least four Syrian servicemen, 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 around 3 p.m.

It marked the second time during Syria’s civil war that Israel has accused Iranian forces of launching a rocket attack from the country, where Tehran has sent troops to back President Bashar 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.

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.

Though 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 continue.

“Israel has flagrantly breached international law. This is an act of aggression against a sovereign state,” said Andrei Krasov, deputy chairman of the Russian parliament’s defense committee, told Interfax news agency.

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

“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.”