Putin doesn’t care one bit about ISIS. He cares about keeping Assad in power. He wants access to Syrian ports on the Mediterranean. That is it. It is classic Soviet doctrine, to mitigate choke points bottling up the Russian Navy.
Its true. With Crimea as well. But the same can be said of us. We want those ports out of his hands and will tolerate ISIS (or whoever) as long as it gets Assad out of power and makes that happen.