I'll go along with fear. We all fear what we cannot understand or cannot control. 9/11 taught us that we are vulnerable. It stripped away our innocence and forced us to realize that not everyone loves us. That regardless of how much aid we send, they just don't love us. This has been a great revalation to some people and it scares them.
all of a sudden, their lives may be threatened at any time and their Government, which has always taken care of them, can't prevent it. So the fear gets sublimated and turns to anger and, instead of discussing our differing points of view rationally and calmly, we become hostile when confronted by any opposition
There were similar feelings during Viet Nam and I witnessed some pretty ugly stuff at some demonstrations from both sides of the fence.

troll