For the first time since Afghanistan in the 1980s, the Russian military for the past year has been in direct combat with rebel forces trained and supplied by the C.I.A. The American-supplied Afghan fighters prevailed during that Cold War conflict. But this time the outcome — thus far — has been different.

“Russia has won the proxy war, at least for now,” said Michael Kofman, a fellow at the Woodrow Wilson Center in Washington.

Russia’s battlefield successes in Syria have given Moscow, isolated by the West after its annexation of Crimea and other incursions into Ukraine, new leverage in decisions about the future of the Middle East.

The Obama administration is now talking with President Vladimir V. Putin’s government about a plan to share intelligence and coordinate airstrikes against the Islamic State and other militant groups in Syria, and Mr. Putin has thus far met his goals in Syria without becoming caught in a quagmire that some — including President Obama — had predicted he would…

At the same time, some military experts point out that Mr. Putin has saddled Russia with the burden of propping up a Syrian military that has had difficulty vanquishing the rebels on its own.