Because of the September 11. 2001 attacks
Because the 9/11 attack.
Its was not only because of the 9/11 attacks. America already knew about the awful things going on there before the attack. It was just that up until then, we wernt doing anything about it. Look it up on google... Or Nationalgeographic.com .... I'm sure you'll find lots of information to fill your need.
Because of9/11. The word war doesnt sit right with me maybe the right word is invasion.