Obama's Stance

Neither the Sunni Nations nor Obama can afford to go against Putin (who is also aligned with Iran) directly. Because this could start a nuclear war. However, we can go against ISIS because of Barbarity to show Russia and Iran that the U.S. and the Sunni nations are not ineffective. Obama can also arm Sunni Rebels who aren't jihadists like ISIS to be more effective against Assad.

So, Obama's stance could be seen like this: "I'm getting rid of ISIS because I can't get rid of Russia and Iran and Assad directly without starting a nuclear war and ending all life on earth."

This is the best way to say this.