Russian forces opened fire on Israeli fighter jets while they were allegedly carrying out airstrikes in Syria last week, Israel’s Channel 13 News reported on Monday.

According to the channel, the incident happened on Friday as Israeli pilots attacked Iranian-linked targets in southwestern Syria. Russian forces reportedly opened fire on the pilots using advanced S-300 anti-aircraft missiles. Syrian state media said Israeli missiles targeted the town of Masyaf during the alleged airstrikes, killing five people – including a civilian – and injuring seven others.

The Syrian Observatory for Human Rights, a UK-based war monitor, said the Israeli fighter jets hit weapons depots and sites belonging to Iranian militias during Friday’s airstrikes. According to Channel 13, Russia fired at the Israeli jets as they were leaving the area and did not present a real threat to the pilots.

If confirmed, this incident could mark a significant shift in Moscow’s attitude towards Jerusalem. Historically, Israel has had strong ties with Russia and coordinates with Moscow on airstrikes against Iranian targets in Syria. Russia is a close ally of Syrian dictator Bashar al-Assad and operates inside the war-torn country. Israel rarely ever acknowledges its activity in Syria but views Iranian activity there as a major national security threat.

The report said the Syrian military fired off dozens of anti-aircraft missiles, which have been largely ineffective at halting the hundreds of Israeli strikes on Syria in recent years. However, this time the S-300 batteries also opened fire as the jets were departing the area, Channel 12 said. The report noted that Syria’s S-300 batteries are operated by the Russian military and cannot be fired without their approval.

The report said that the S-300 radar did not manage to lock onto the Israeli jets and thus did not present a serious threat to the IAF fighter jets. If confirmed, however, this would mark the first use of the S-300s against the IAF over Syria and would be a worrying development for Israel,

which has carried out hundreds of airstrikes inside Syria in the course of the country’s civil war and since, targeting what it says are arms shipments bound for Lebanon’s Iran-backed Hezbollah terror group and other Iranian-linked sites. Israel rarely acknowledges or discusses such operations and there was no confirmation of the raid or the S-300 launch from the IDF.