Update 4: The Russian Ministry of Defense cleared up the confusion surrounding the overnight downing of a Russian Ilyushin-20 reconnaissance plane on Tuesday when a spokesman revealed that Israel was indeed responsible for the attack, which resulted in the deaths of 15 Russian servicemen.

According to the Wall Street Journal, the plane was accidentally brought down by an aging Syrian S-200 defense system after Russia had scrambled its jets to respond to an attack by four Israeli F-16s on Syrian government targets. Israeli notified Russia of its attack over a shared hotline less than a minute before beginning the strike, giving the Kremlin little time to respond.

"As a result of the Israeli military’s irresponsible actions 15 Russian servicemen died," said Defense Ministry Spokesman Gen. Igor Konashenkov.

Israel has carried out roughly 200 strikes in Syria over the past year and a half as it pushes back against Tehran's growing presence in the war-torn battle zone.

Moscow has the right to "respond adequately" to the attack, Konashenkov said.

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Update 3: In a breaking report CNN has cited Pentagon officials who say the missing Russian aircraft with 14 service members on board, now subject of a Russian search-and-rescue operation, was accidentally shot down by Syrian missile defense.

Pentagon sources say further that Israel was responsible for the nighttime attack, which reportedly involved strikes by air and possibly by sea from the Mediterranean. Israel has yet to issue comment.

But Russia says its radar picked up a French warship firing in the area just before the Russian patrol aircraft went down.

According to CNN:

A Russian maritime patrol aircraft with multiple personnel on board was inadvertently shot down by Syrian regime anti-aircraft artillery on Monday after the Syrians came under attack by Israeli missiles, according to a US official with knowledge of the incident The US official said the regime was actually trying to stop a barrage of Israeli missiles. A second official confirmed that Israel was responsible for the missile strikes on the Syrian regime.

The Pentagon sources cite a radio broadcast in making the claim of an accidental shootdown, however it's not clear if their assessment is based on actual US intelligence or speculation.

Il-20 is electronic intelligence (ELINT) aircraft. pic.twitter.com/kkxf8iE8rx — Military Advisor (@miladvisor) September 18, 2018

The CNN report continues:

The US found out about the incident because Syrian forces broadcast an emergency search and rescue radio call on an international frequency. The US then got a direct message from another country about the type of aircraft and circumstances of the incident. The official would not identify that country, but it is likely that Russia is the only nation that would know exactly what type of aircraft was shot down.

The Pentagon formally denied any US role in the attack soon after it was first reported.

This is sure to evoke a new round of dangerous and fierce US-Russia controversy over Syria as already there are accusations and counter-accusations amidst the breaking reports.

So a Russian Military Plane with 14 personnel on-board goes missing the same time Israel was launching strikes in Syria, and Syrian air defenses were firing en-mass in response, and a French Frigate reportedly launched a missile at the same time near the Syrian coast. #Problem — Danny Makki (@Dannymakkisyria) September 18, 2018

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update 2: The Russian Ministry of Defense (MoD) reports in the aftermath of Monday night's wide-scale attack on multiple locations in Syria that a Russian military Il-20 aircraft with 14 service members on board is not detectable via radar, and that a rescue mission is underway.

And alarmingly RT claims the following citing the Russian Defense Ministry: Russian radars also registered the launch of missiles from a French frigate in the Mediterranean on the evening of September 17. The MoD also said it observed a French frigate in the area at the time.

Reports TASS via a Russian defense official:

"On September 17, at about 11:00 Moscow time, the connection with the crew of the Russian Il-20 aircraft was lost over the Mediterranean Sea when the plane was returning to the airbase of Khmeimim, 35 kilometers from the coast of Syria," the official said. The ministry specified that "the mark of IL-20 went off the radars disappeared during the attack of four Israeli F-16 aircraft on Syrian targets in the province of Latakia." "At the same time, the Russian radars fixed missile launches from the French frigate Auvergne, which was in that area," the Defense Ministry said. The official also said that there were 14 servicemen on board and their fate is unknown. The command of Russia’s air base at Khmeimim launched a search and rescue operation.

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update: The Pentagon has formally denied that tonight's massive sustained attack on Syria had US involvement.

US-funded VOA News reports a Pentagon spokesman issuing the following statement: "I can unequivocally say this is not us," said Navy Cmdr. Sean Robertson.

Regional sources report, citing Syrian officials, that Monday night's attack involved "cruise missiles fired from the sea".

Pentagon spokesman Navy Cmdr. Sean Robertson tells VOA on Syrian claims of engaging missile targets over #Latakia "I can unequivocally say this is not us." #BREAKING @VOANews — Carla Babb (@CarlaBabbVOA) September 17, 2018

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Earlier:

Another attack on Syria has occurred tonight on multiple locations in what is the largest sustained series of what are believed to be Israeli or possibly US air strikes in months. But hugely significant is that early reports suggest Russia's S-400 anti-missile missile defense system engaged the inbound rockets.

On Monday night Syrian state-run SANA confirmed multiple missiles fired "from the sea into Lattakia city" in "an aggression from unknown source" which state media says involved successful intercepts by Syrian missile defense.

British-Syrian journalist Danny Makki, currently reporting from the ground, says the attack "lasted for a total of 1 hour 30 minutes" and missiles soared over four cities including Latakia, Tartus, Homs and Hama — with rockets and explosions lighting up the sky especially over the coastal towns.

Though it appears another Israeli strike - as it came less than two days following an attack near Damascus - the details are still unknown, and some observers are speculating it could be an American attack, given that at least some of the missiles were fired from the sea.

SANA reports "an aggression on Lattakia has targeted the Technical Industries’ establishment" adding that "the air defenses intercepted and downed a number of the missiles".

Multiple journalists in the region further said that Syrian air defenses were activated across four provinces including Latakia and Tartus on the coast, as well as over Homs and Hama which are more inland.

The initial major strike on Latakia, located on the Syrian coast, reportedly targeted a Syrian Scientific Research Center (SSRC) facility, and newly published video and images from Syrian sources show massive fireballs lighting up the sky.

Video footage showing the impact of missile strike this evening near #Lattakia, #Syria pic.twitter.com/Tdz377duJo — Danny Makki (@Dannymakkisyria) September 17, 2018

But significantly the location of the strike is in the vicinity of Russia's Hmeymim airbase, and there are early unconfirmed reports that Russia engaged the inbound assault via its advanced S-400 system.

BREAKING: Missile strikes target infrastructure in Latakia, Syria short time ago. Reports attributing attack to Israel. pic.twitter.com/OuZyVb7eSN — Israel Breaking (@IsraelBreaking) September 17, 2018

According to the Middle East Institute's Charles Lister, "Reports suggest Russia air defenses in Hmeymim participated in attempting to repel tonight’s strikes in Latakia."

Lister continued, "*IF* that’s true, that’d be a significant development. Some reports also say strikes came from sea; leading to accusations of a U.S naval cruise missile attack."

Unconfirmed local eyewitness accounts say that two hostile aircraft were shot down during the lengthy assault.

A number of videos are circulating on Syrian social media which purport to show successful Syria or Russian missile defense intercepts during the sustained attacks.

The air defenses in #Latakia sky. Assad supporters said there were two planes shot down

No confirmation pic.twitter.com/vDEuZxuLBG — Aghiad AL Kheder (@aghiad_alkheder) September 17, 2018

As yet, there's been no confirmation of who carried out the attack; however, a report early this month cited Tel Aviv sources who confirmed that Israel's Air Force has conducted 200 attacks on locations inside Syria over the course of the past 2 years alone, according to Reuters.

The major escalation comes just after Russia's Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan met Monday to announce that a demilitarized zone in Idlib will be formed by October 15.

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