Militants are being poised to stage a chemical weapons attack in order to frame Damascus, providing a pretext for retaliatory strikes.
The war that erupted in 2011, one of the most devastating conflicts since World War II, has displaced more than half of Syria's population, including more than five million beyond its borders.
The Kremlin has provided no evidence to substantiate its claims, which include the assertion that United Kingdom private military company Olive Group, under the direction of the United Kingdom government, is directly supporting these activities in Syria.
Following up on concerns expressed over the weekend that a "false flag" attack might be used as a pretext for a U.S. attack on Syria, Russian Defense Ministry officials say they are deeply concerned by signs of a U.S. military buildup around the area, seemingly setting up for just such an attack. North Atlantic Treaty Organisation spokeswoman Oana Lungescu, meanwhile, told Haaretz on Tuesday that the navy "has dispatched substantial naval forces to the Mediterranean, including several ships equipped with modern cruise missiles".
Tehran has given the Assad regime political, financial, and military backing throughout the country's seven-year uprising.
In April, the US, France and Britain launched joint missile strikes on Syrian targets in response to an alleged chemical weapons attack in the town of Douma that left scores of people dead.
Since President Donald Trump took office, the USA has twice struck Syria in response to what it called incontrovertible evidence of chemical attacks on civilians.
That attack was carried out after a report of chemical attack, which came from the White Helmets, an infamous Western-backed aid group that has been caught red-handed working with the terrorists and producing fakes to smear the Syrian government and its allies.
A Russian navy battleship fires missiles during a rehearsal of the Russian Navy Day parade in Sevastopol, Crimea, 2015.
This time, Russian Federation looks like it's up to more than simply conducting a public relations battle with the US.
But even with its massive naval presence, Moscow doesn't stand a chance of stopping any United States attack in Syria, Omar Lamrani, a military analyst at the geopolitical-consulting firm Stratfor, told Business Insider. "If the United States comes in and launches cruise missiles" - as it has in past strikes - "the Russians have to be ideally positioned to defend against them, still won't shoot down all of them, and will risk being seen as engaging the U.S.", which might cause USA ships to attack them.
"To be frank", Lamrani said, "the USA has absolute dominance" in the Mediterranean, and Russia's ships wouldn't matter.
The Russian Ministry of Defence said on Monday it had noticed Washington was building up its military forces in the Middle East in preparation for what Moscow feared was a possible strike on Syrian government forces, Russian news agencies reported.
Russian President Vladimir Putin said before talks with German Chancellor Angela Merkel earlier this month that everything needed to be done for Syria refugees to return.
"Syria is in a very, very important juncture".