From overflight requests and grainy photos of fighter jets to social-media posts showing Russian marines in Syria, there are mounting signs that Moscow may be ramping up its military presence in the war-torn Middle East nation.
As Western governments struggle to grasp the extent of Russia's involvement in the Syrian civil war, a more pertinent question is sometimes obscured: What does Russia want?
The answer? As much as it can get.
Like he did when he sent troops to seize Crimea and backed a rebellion in eastern Ukraine after a Moscow-friendly leader's power evaporated in 2014, Russian President Vladimir Putin seems to be taking action in Syria -- and preparing to squeeze as much benefit as he can out of a fluid and chaotic situation.
And as in Ukraine, Russia is likely to test the boundaries and stop when it runs up against one that seems insurmountable -- or at least pause, regroup, and once again reassess its options.
The following is a rundown of the goals Putin may be pursuing, from the most ambitious to the most modest.
Grand Bargain
For years, Russia has called for a shake-up of a global security system it says is badly skewed by the dominance of the United States, and a greater say for Moscow in making new rules. Putin may see the Syria crisis as Russia's best chance to make this happen, trading his country's support in the fight against Islamic State militants for a seat at the table in talks on a new security architecture that would reduce NATO's clout, leave Ukraine neutral, and give Russia a prominent place. Such hopes may be driving his vocal calls for "an international coalition against extremism and terror," and a flurry of diplomacy that has accompanied them.
Thaw
Incensed over Moscow's intervention in Ukraine, Washington and the West are in no mood to give Russia a role building a security system out of the scraps of one they accuse Putin of trying to tear apart. Russia's refusal to abandon support for Syrian President Bashar al-Assad makes such a prospect even harder to swallow. A more modest, but still sweeping goal -- Grand Bargain Lite -- would be this: Use Russian support against Islamic State to stoke a thaw in relations with the West, then reap potential benefits ranging from relief from the sanctions imposed over its role in Ukraine to restoration of its seat in what was, until Russia's suspension in 2014, the Group of Eight leading industrialized nations.
Big Bluff
Again, any Russian hopes for a tradeoff may be misplaced: The United States says it does not do such linkages. And suspicions that John Kerry's trip to see Putin in Sochi in May meant a quid pro quo was in the works were quashed when the U.S. secretary of state phoned Foreign Minister Sergei Lavrov on September 5 to say that rumblings of a Russian buildup were far from a reassuring sign that help against IS militants is on the way. On the contrary, Kerry said, a stepped-up Russian presence could lead to more civilian deaths, create more refugees, and cause "confrontation" with the anti-IS coalition in Syria.
Russia may have expected that response, or even been angling for it. By calling for a coalition against extremism, but insisting that Assad's government is crucial to the battle against IS, Russia could be preparing to throw up its hands theatrically and accuse the United States of being two-faced in the fight against terror -- a claim Putin has made many times in the past. Unless the United States backs down on the issue of Assad, whom Washington wants out, Putin may make it again, with the world watching, when he attends the UN General Assembly this month for the first time in a decade.
Saving Assad
Playing down the reports of a military buildup, Russian Foreign Ministry spokeswoman Maria Zakharova said Lavrov told Kerry that Moscow has always supported the Syrian authorities in "their fight against terror." That language has been used by Damascus and echoed by Moscow since early in the Syrian crisis, long before IS militants entered the country, when Assad used government forces to crush pro-democracy protests. Western officials say the real purpose of the weapons and advisers Moscow has sent has been to bolster Assad, who has given Russia its biggest foothold in the Middle East.
The reason for a Russian buildup could be simple: The task of supporting Assad has gotten tougher as his forces have lost ground to IS fighters and an array of other militant and rebel groups, leaving the government in control of a fraction of Syria around Damascus and the Mediterranean coast. That includes Tartus, the port city that hosts Russia's only naval facility in the Mediterranean, and Assad's ancestral homeland in Latakia Province, where media reports have cited U.S. administration officials as saying Russia has sent a portable air-traffic control station and prefabricated housing units for hundreds of people.
Best Of The Worst
Russia has used both military aid and diplomatic maneuvering to keep Assad in power, insisting throughout the crisis that a political solution cannot be conditioned on his exit. That does not mean, however, that Putin hasn't thought about how to preserve Russia's interests if Assad is pushed out. The least ambitious goal of Russia's reported buildup may be just that: a move to maintain a foothold in Syria -- and try to secure a strong say in what comes next -- in the event that Assad is defeated on the battlefield or ousted as part of a peaceful settlement.