The Russian presence in Syria has grown to nearly 4,000 personnel — including military and civilian support staff — a sign that Russian President Vladamir Putin is digging in long-term to prop up the regime of Syrian President Bashar al-Assad.
The latest details of the Russian footprint come from US officials who have been monitoring Russia's moves in Syria since it started conducting bombing raids on behalf of Assad in late September.
Before Putin came to Assad's aide, Russia maintained a smaller force of 2,000 personnel in the country, which is a longtime Russian ally.
"Last month, they launched air operations really fast, and the logistical support was just not there at the time," explained Michael Kofman, a leading Russian expert at the Wilson Center. "So to sustain them, all these people have arrived to support their operations."
US officials told Reuters on Thursday that the Russians are operating out of several facilities in Syria: an airfield in the Assad stronghold of Latakia, the port in Tartus, and three forward bases for helicopter gunships near the front lines in Hama, Sharyat, and Tiyas. The latest intelligence indicates the Russia's air fleet in Syria is made up of 34 fixed-wing aircraft and 16 helicopters.
Victoria Nuland, assistant secretary of state for European and Eurasian Affairs, said on Thursday that Russia is also deploying more soldiers on the ground near the front lines.
"Russia is fielding its own artillery and other ground assets around Hama and Homs," she said.
Such a display of force so far from Russia's borders is unprecedented since the fall of the Soviet Union. But Kofman said he doesn't expect Russia to establish a significant presence on the ground going forward. Rather, the show of airpower is intended to raise moral for the ground troops backing Assad, and clear the way for an advance.
While the US and it's allies have made fighting the Islamic State a major priority in Syria, Russia is less concerned with the militant group. So far, around 80 percent of their strikes have hit non-Islamic State rebels fighting the Assad regime, according to open-source analysis conducted by Reuters.
That fits with Russia's overall view of the conflict, said Kofman.
"The Islamic State is an American problem, it's not a Russian problem," he said.
Russia intervened initially because other rebel groups, like the Al-Qaeda aligned Nusra Front, and smaller rebel groups backed by the CIA, Saudi Arabia, and Turkey were threatening Assad-held territory.
"The Islamic State is too far to the east to really be an immediate threat to Assad," Kofman explained. "For Russia they are.... a third order problem."
By that metric, Russia has done quite well so far. While Assad has not yet retaken significantly territory, the Russians now rule the skies over the heads of his most immediate enemies. "All those groups are now under Russian air power, " Kofman said. "And not a single one of their planes or helicopters have yet come down."
By all accounts, the Russians aren't leaving anytime soon.
"It looks like we are going to see several offenses as part of this military intervention, they are in for another few months of action," Kofman said. "But while we will see some high intensity fighting on the ground, the bulk of that will be conducted by Iran, Hezbollah, and Assad's troops, under the cover of Russian airpower."
Meanwhile, the conflict has raged for 4 1/2 years, claiming over 250,000 lives and displacing over 7.5 million people. The Assad regime, not the Islamic State, is responsible for the majority of that carnage.