There are Russian voices within the government and military pushing for a ground operation.
Russia's intervention in Syria has been costly - billions of dollars have already been spent, and the country is suffering from an economic crisis.
The Kremlin never wanted a permanent war, and it can't just pull out of a conflict that has brought it back into the international arena.
That is why some analysts suggest a "Stalingrad" in Syria is what the Syrian government and its allies need - a final battle to decisively end the war. And that would require ground troops.
(The Battle of Stalingrad (23 August 1942 – 2 February 1943 was a major battle on the Eastern Front of World War II in which Nazi Germany and its allies fought the Soviet Union for control of the city of Stalingrad (now Volgograd) in Southern Russia, on the eastern boundary of Europe.
Marked by constant close quarters combat and direct assaults on civilians by air raids, it is often regarded as one of the single largest (nearly 2.2 million personnel) and bloodiest (1.7–2 million wounded, killed or captured) battles in the history of warfare. The heavy losses inflicted on the German Wehrmacht make it arguably the most strategically decisive battle of the whole war. It was a turning point in the European theatre of World War II; German forces never regained the initiative in the East and withdrew a vast military force from the West to replace their losses.)