Without going into what are probably the actual reasons for these war the public justification for them has never been that people are "upset about this one par

Without going into what are probably the actual reasons for these war the public justification for them has never been that people are "upset about this one particular event". The US and its allies aren't directly avenging the deaths of those 3,000 people. Rather it's recognized that if the perpetrators had the chance they would probably have killed 30 thousand, or 3 million. So the public justification for the "War on Terror" has been to prevent similar future events. See e.g. this interview with Tony Blair where he makes that exact point: http://www.thedailyshow.com/watch/tue-september-14-2010/exclusive---tony-blair-extended-interview-pt--1 http://www.thedailyshow.com/watch/tue-september-14-2010/excl...