Everybody is asking why the Russian air campaign against IS seems to work while the US, with over 25,000 sorties, doesn’t.
The reality is in the motivations.
Russia wants to defeat IS as it is important that Assad remains in power as it is one of the few friends in the Middle East (with Iran and soon Iraq). Even if Assad is evil.
The US aim to contain IS (not destroy it) as it does not want Assad to retake control nor the moderate rebels to win (which will surely rebrand themselves as Al Qaeda as soon as they win).
Both Russia and US can use the IS scarecrow to keep us in fear and, in a weird Keynesian way, boost the economy and employment ( weapon manufacturing) and refining weaponry.
For a few is quite a win win scenario _ realpolitik at its best (worst).