Russia is just expanding their influence. War zones are a perfect place to expand if you have the ability to defeat either side. Question is...which side does Putin want to defeat?
He wants to preserve Syria as a Russian client state, which it has been for more than a half century, and fill the vacuum left by the Obama and his gang of idiots’ (Hillary Clinton, please come to the white phone) abdication of American sanity. So the enemy are ISIS and the other Sunni groups (many financed and armed by Obama and the gang) fighting Assad. Portraying himself as defender of the minority Christians and Kurds (who share Turkey as a blood enemy with Russia), and supplanting village idiot America as the arbiter and ally with the most powerful country in the region besides Israel (Iran) are sweet frosting on the cake.