For decades, Russia has been trying to rebuild its influence in the Middle East. But after the rapid collapse of the Assad regime in Syria, the Kremlin is scrambling to salvage whatever it can.

President Vladimir V. Putin sought to spin events in Syria as a success for Russia, which provided crucial military support for President Bashar al-Assad during the country’s long and brutal civil war, and received two important military bases in return.

“We came to Syria 10 years ago to prevent the creation of a terrorist enclave there,” he told a marathon news conference on Thursday. “We have achieved that goal, by and large.”

The reality of Russia’s situation is quite different from Mr. Putin’s rosy assessment, according to military experts, political analysts and a U.S. government official. If the rebel factions that are now leading Syria decide to expel the Russian forces from the two bases, Moscow will be left without the resources or the real estate to maintain a significant military presence in the region, they said.

One veteran Russian military analyst, speaking anonymously out of concern for the safety of his relatives still in Russia, called Moscow’s current maneuvering “diplomatic dancing” that did not comport with reality.