The US just called out Russia over those 'military experts' seen in Syria

Reports that Russia is ramping up its military involvement in Syria have US officials concerned and outright skeptical over Russian President Vladimir Putin's intentions.

Putin has said that Russia wants to "create some kind of an international coalition to fight terrorism and extremism."

The Russian Foreign Ministry confirmed on Wednesday that Russian military advisors are in Syria - but insisted it was just to advise the regime in its "fight against extremists."

The US State Department isn't buying it.

"Russia is not a member of the coalition against ISIL, and what we've said is that their continued support to the Assad regime has actually fostered the growth of ISIL inside Syria and made the situation worse," State Department spokesman John Kirby said on Wednesday, using an acronym for the Islamic State (aka ISIS and Daesh).

"If they want to be helpful against ISIL, the way to do it is to stop arming and assisting and supporting Bashar al-Assad."

Russian drones and fighter planes are surveilling non-ISIS rebels in the country's north - Assad considers all rebels "terrorists" or "extremists" - and Russian armored personnel carriers with Russian-speaking troops were involved in fighting.

Russia has also set up an air-traffic-control tower and brought housing units for up to 1,000 personnel to Latakia in the country's west, and Reuters reports that two tank landing ships and additional aircraft have arrived.

The news comes as al Qaeda-linked rebels took full control of the Idlib province, which borders Latakia and is just the second province no longer under government control (along with ISIS-controlled Raqqa).

"Assad has lost significant territory over the past months; Putin is not about to tolerate his ouster," geopolitical expert Ian Bremmer, the president of Eurasia Group, told Business Insider in an email.

Over the course of the 55-month Syrian conflict, Russia has provided the Assad regime with supplies - including guns, grenades, tank parts, fighter jets, advanced anti-ship cruise missiles, long-range air-defense missiles, military officers as advisers, diplomatic cover, and lots of cash.

The US is moving to block the latest buildup by asking countries such as Greece and Bulgaria to shut their airspace to Russian transport planes. Over the weekend, a Russian plane reportedly landed at the same airfield in Latakia, flying over Greece and Bulgaria to transport Russian troops to Syria.

Though Bulgaria has complied, Greek officials say they are still looking into the request.

Unconfirmed sightings of Russian infantry vehicles and military advisers in Syria has prompted further rumors that Putin has already put boots on the ground and may be preparing a large-scale counterterrorism operation alongside Iranian proxy militias.

The operation has less to do with fighting ISIS and more to do with countering Western actions that have bolstered rebel forces in the north and threaten to weaken Assad further.

"If the West succeeds in turning the tide of the war while Assad is vulnerable, the political outcomes in Syria are more likely to be dictated by the US," Bremmer said. "Which means Putin needs to bolster Assad now."

Kirby reiterated that Russia's actions have not been helpful.

"The most productive thing that they can do, if they are serious about getting after extremist networks in Syria, is to stop arming and abetting and aiding Bashar al-Assad, the same man who has by his own brutality and violence on his own people allowed ISIL to grow and to spread inside his own country," he said.

For years, Assad has argued that he is fighting terrorism - when, in fact, the US and others have accused him of facilitating the rise of ISIS.

"The [Assad] regime is a terrorism generator of epic proportion, engaging in state terrorism against its own people and inciting terrorism from its opponents," a recent Soufan Group note reported.

"There is no justifying the actions of a group like the Islamic State or al-Nusra ... but the Assad regime's wholesale slaughter of civilians provides the groups with radicalized supporters far faster than Assad's military can then fight them."