Quite a few things were going on around then, but, I would still argue that it was building even before that.
We had the Cold war, and then that ended. For a long time God and Country where how we identified. That ends in the 90s when the USSR collapses. God and Country become less important and those power structures start losing power. There starts a big push for God and Country again, and then we are hit with 9/11.
That was the foundation of something that has been horrible. We were becoming more secular which is good, and that got push back from the religious leaders. People were dismissing religious dogma and then we get hit with terrorism. So, we go back to our roots and God/Country take over.
Now the conversation shifts to, fighting to win for God/Country is the moral position, and anything you can do is thus moral. That right there is what screwed us. When you feel justified that anything you do is moral, you will do some stupid/horrible shit.
This is what has me worried, because, the left is picking up that tool right now. Violence is fine, because its on the right side of morality. If that becomes popular enough, then we are all fucked. Both sides fighting each other because each side represents evil/immorality.