Syrian anti-aircraft artillery reportedly responded to a number of Israeli missiles that were launched towards the coastal city of Latakia when it accidentally shot the Russian maritime patrol aircraft, according to a USA military official cited in the report.
Russian radars also registered the launch of missiles from a French frigate in the Mediterranean on the evening of September 17.
A Syrian facility linked to the country's chemical weapons program was bombed on Monday night, triggering Syrian air defenses, state media reported.
A Russian military aircraft with 14 people on board has disappeared from radar after flying over Syria, Russia's defence ministry says.
Earlier in the day, Russian Federation and Turkeyreached an agreement over a partial demilitarization of the Idlib province, which is the last remaining stronghold of anti-government insurgency and al-Qaeda-linked terror groups in Syria.
"Our air defences are countering hostile missiles coming from the sea towards the city of Latakia, and a number of them have been intercepted", a source told the state news agency.
A French military source, however, denied any French involvement in disappearance of the Russian plane.
The Syrian Observatory for Human Rights, a UK-based war monitor, said huge explosions were heard in the city.
Meanwhile, a United States official with knowledge of the incident claimed the Russian plane had been inadvertently shot down by the Syrian anti-aircraft artillery after the Syrians came under attack by Israeli missiles.
Water -- not wind -- is the deadliest storm hazard
This general motion is forecast to continue today with a decrease in forward speed as it gets over the Caribbean Sea. Tropical storm conditions are possible within the tropical storm watch area, also beginning late this morning.
The Syrian government regularly accuses Israel of targeting its military positions.
No further details were immediately available. The plane was 35 kilometers off the coast of Syria when it vanished.
The Observatory said at the time that the September 4 attacks were believed aimed at Iranian military posts.
The zone will be established by October 15 and be 15 to 20 kilometres deep, with troops from Russian Federation and North Atlantic Treaty Organisation member Turkey conducting coordinated patrols, President Vladimir Putin said after meeting with Turkish President Recep Tayyip Erdogan in Sochi.
The aircraft was shot down by an anti-aircraft system the Russians sold to the Syrians several years ago, the official said.
A spokesman for the Pentagon told CNN that the missiles were not fired by the US military but would not speak as to who was behind the strikes.
Syrian regime pauses Idlib ground offensive.
The port city of Latakia is home to the family of Syrian President Bashar al-Assad, and a bastion of loyalty to his regime.