Has Syria become a Russian-American proxy war?

While President Obama has repeatedly dismissed the idea of a proxy war in Syria, experts are divided on whether that is already happening.

Russia said Thursday that it would reduce the frequency of airstrikes in Syria as government forces on the ground move to cover the changing front lines of the Islamic State.

The announcement comes just days after rebel forces said that they had been supplied with American-made TOW anti-tank missiles, stoking fears that the United States is increasing its role in the years-long Syrian conflict that now includes Russia.

These 500 or so missiles have a range of 2.6 miles and "have been employed to deadly effect against the regime forces," reports The Christian Science Monitor’s Nicholas Blanford.

As the increasingly well-armed rebels continue to fight the Russian-backed government regime, "the Syrian conflict is edging closer to an all-out proxy war between the United States and Russia," wrote The New York Times on Tuesday.

President Obama has repeatedly dismissed the idea of a proxy war in Syria.

"We’re not going to make Syria into a proxy war between the United States and Russia," he said at an Oct. 2 press conference. "This is not some superpower chessboard contest.  And anybody who frames it in that way isn’t paying very close attention to what’s been happening on the chessboard."

But not all experts agree with him. Some of the debate comes down to semantics.

Stephen D. Biddle, an adjunct senior fellow for defense policy at the Council on Foreign Relations, told NPR that he defines a "proxy war" as "as an outside actor advancing an agenda by using local fighters."

By that definition, "the simple answer would be yes," he said. "But it's also incomplete, because there are lots of proxy wars going on in Syria. And it's not clear that the one between Russia and the United States is the most important."

John McLaughlin, a practitioner-in-residence at Paul H. Nitze School of Advanced International Studies at Johns Hopkins University, told NPR he doesn’t see the conflict as a proxy war – yet.

"But the situation is very fluid and could move in that direction," he said.

Another expert warned that "the term 'proxy war' overstates US-Russian strains over Syria."

Even with American-made missiles, "the US has not, and I don't think will, actively oppose the Russian move," wrote Cliff Kupchan, chairman of the global risk analysis firm Eurasia Group. "US strategy is not proxy war, but to let President Vladimir Putin dig his own hole in the morass that is the Syrian civil war."

Some critics also say that Russian intervention is less about fighting the US than wooing regional allies.

"That Vladimir Putin is out to save Syrian President Bashar al-Assad seems to be of little doubt," writes the Monitor’s Howard LaFranchi on Wednesday. "But increasingly, it appears the Russian leader is intent on making a broader point through his muscular military intervention in the Syrian conflict, and it has to do at least in part with the United States."