First of, my respect does go out to those that lost their lives.
Maybe if the USA stopped clandestinely taking over other people's governments and stealing all of their natural resources, they might stop committing terrorist attacks against us. Maybe it really is that simple.
Don't worry though, the list of countries America has done this to in the past 100 years consists only of:
Syria, Iran, Guatemala, Tibet, Indonesia, Cuba, Democratic Republic of the Congo, Iraq, Dominican Republic, South Vietnam, Brazil, Ghana, Chile, Argentina, Afghanistan, Turkey, Poland, Nicaragua, Cambodia, Angola, Afghanistan, Venezuela, Haiti, Gaza Strip, Somalia, Libya, Panama and Grenada... that's all! Oh yeah, there's also a long list of oppressive regimes we didn't create, but prop up economically and militarily, like Saudi Arabia and Israel!
http://en.wikipedia.org/wiki/Covert_United_States_foreign_regime_change_actions