Why would the world turn against us?
Good question - normally wouldn't happen (except for via the UN council) because of the combination of NATO and Russia's obvious aggression designed to develop/increase its hegemony.
On the other hand, Obama doesn't have a record of being involved in conflict in a way that is beneficial to us or our allies - he probably has a well-developed plan to make a lot of folks mad at us while he thumbs his nose.
The world will not turn against us....... the world will turn against Obama