as an Aussie, i think 9/11 was a tragic event, but i think a war wasnt a need, especially now since they have backed out and forgetting all they promised to the Afghan people. I was actually reading something this morning which was about the interpreters that the US used, they promised to take them into the states and give them citizenship given they meet 4 requirements. Now, the interpreters have been labelled as traitors to the Taliban and the people of Afghanistan and are being spied on and hunted down and killed, same with their families, and the US broke their promise to not help them out... even when they meet those 4 requirements, and as a result they are being hunted down and killed.
Anyway, thats not very on topic, simple answer from me: It was a tragic event, but a war wasnt needed.