Some 30 missiles triggered huge explosions near Khmeimim air base, believed to house weapons for Iran, The Telegraph reports.
Huge explosions were reported near Latakia in Syria overnight as missiles rained down.
Israel is suspected of launching missiles overnight into Syria, striking close to a Russian air base believed to house weapons for Iran.
Up to 30 missiles were said to have targeted an area near to Khmeimim air base, near the coastal city of Latakia, triggering a series of huge explosions.
Video footage showed streaks of bright orange light in the night sky, as air defences attempted to intercept the missiles. A huge blaze could be seen for miles close to Khmeimim.
There also appeared to be secondary explosions, suggesting that weapons or munitions had been hit.
The strike could mean Israel, emboldened by its success in destroying Hezbollah targets in Lebanon, is stepping up its campaign against Iranian-linked assets in Syria, despite the risk of provoking Russia.
The Syrian Observatory for Human Rights said Russian and Syrian air defences attempted to intercept missiles for at least 40 minutes in Latakia.
Other reports in Syrian media suggested the strike targeted a warehouse inside the base following the arrival of an Iranian cargo plane, suspected of delivering weapons.
The strike, according to those reports, came an hour after an Iranian Qassem Fars Airlines plane landed. The airline has long been linked to Iran’s Revolutionary Guards Corps and has previously been accused of transferring weapons to terrorist proxies.
Rybar, an influential Russian war blogger, wrote on the Telegram app that the target was not the base but a warehouse nearer to Jebeh used by both Iran and Russia.
“Some of the missiles were shot down” by the Russian military, he said, “but some reached their target.” He added: “There are even more questions from the Syrians about why the Russian air defence is not helping to repel IDF attacks.”
It is not yet clear what damage has been done to either the base or the surrounding area.
Ukraine’s Centre for Strategic Communications also posted footage of the attack, saying it proved that “Russia’s red lines exist only in fairy tales”. It claimed, without providing evidence, that the air base had been “decimated”.
There was no immediate comment from Israel, which frequently hits targets linked to Iran or its proxy militias in Syria, but rarely claims such strikes.
Michael Horowitz, a geopolitical expert and former IDF soldier, said that in the past Iranian planes have used Khmeimim to deliver weapon shipments to Hezbollah.
“Israel is bound to launch airstrikes against any Syrian airport that lets Iranian planes in. Tehran probably thought its best shot was to use Khmeimim because of the Russian presence,” he told The Telegraph.
Khmeimim is one of the most heavily fortified military bases in Syria. Its sprawling airfield is home to Russian fighter jets and bombers, as well as sophisticated long-range and short-range air defences.
It was built in 2015 when Moscow began intervening in the Syrian civil war in support of Bashar al-Assad’s regime and carried out large-scale bombing campaigns.
Moscow has a strong military presence in the province of Latakia, particularly around Khmeimim airbase and a naval facility in the city of Tartus.
Both sites are strategically important to Moscow, which is seeking to grow its presence in the area and has expanded Khmeimim to host bombers close to Nato’s southern flank.
If the strike successfully hit the base or a warehouse near it, it would be “very significant”, said Mr Horowitz.
Israel, he said, has largely not reacted as Russia deployed significant air defences across Syria – particularly in the area hit overnight – to avoid triggering Moscow into stepping up its support for Iran.
“The strike would suggest Israel has decided hitting the vicinity of the base was worth the risks,” he added.
On Wednesday, Israel struck a building in the Syrian capital of Damascus, killing four people, including a consultant for the Iranian Revolutionary Guards and reportedly the son-in-law of assassinated Hezbollah leader, Hassan Nasrallah.
