I am sure that is a small part of it. But I can guarantee you defeating ISIS is the major part.
Lot’s of tinfoil hats in this thread.
Every war is sold to the public with lies, often developed by marketing companies. The demonizing of Russia is yet another prelude to war. You are incredibly naive if you believe what you are being told. A book I recommend is called The Ruses of War by John Quigley.