Which could mean an even lengthier period of destructive stalemate lies ahead.
The Russians will likely use their air power to supplement the Syrian air force in support of embattled Syrian army forces wherever they are most under pressure, playing a role similar to that of the US and its allies in support of the Iraqi and Syrian Kurds.
The latter are combating so-called Islamic State militants, but that is hardly Russia's priority, whatever it may say.
If it was, its jets would be hitting Raqqa in concert with the Western coalition, not the towns north of Homs where regime forces are locked in battle with non-IS rebels, some of them backed by the West.