Well, this is a worldwide problem - and unfortunately there is an element of contagion to it: alienated, disaffected young (generally in their 20s) men (it is what, 99% male?) now frighteningly believe going on a murder spree is an answer.
You're unhappy? Why not blow up a bus.
Feeling down? Shoot up a church.
Don't think you'll ever be a somebody? Kill people in a club.
We need to take care of our young men's mental health - we need to most especially help the Muslim community with their young men because right now, they are the most vulnerable to the call of ISIS.
At the same time, we need to come down hard on all people who are intolerant. We need stricter punishments for those disseminating hate speech in schools, mosques and jails. Perhaps we need internet providers to get more involved? We should be able to extradite radical-preachers etc?
We need to be inclusive and to model that. We need to love more not less...
At the same time, we need to stop our terrible dependency on oil and spend more money on developing alternative energy sources!
As for the USA, they need to ban automatic weapons, at a very minimum, but I imagine hell will freeze over first.