There are wars literally everywhere all the time. You're lucky enough to be in America where you have the luxury of 'security'. What about the Congo, Rwanda, Bosnia, Kosovo, Syria, Egypt, Iraq, Afghanistan, North Korea, Tieniman (sp?) square. Could go on.
9/11 wasn't the reason for all of this, it's just a part of a larger scale of terrorism and war, Americans have pretty much been killin people in the Middle East straight since at least before I was born.
It only has a psychological impact because Americans have the power of media that gets seen everywhere in the world. Which brings me back to my point, it's what the USA does to its people, pulls the blanket over their eyes and only shows them things directly related to them.