I don't think war is the answer. Ignoring the attacks is also not the answer.
The attacks on our country (speaking as an American) and our city (speaking as a New Yorker) and our people (speaking as a human being) were not the act of a foreign country. They were not the act of the followers of a religion. They were not the act of a different race, nor of a different creed. The act of "war" as some people put it was an act of terrorism and evil, carried out by a bunch of individuals.
Some of those individuals are dead. I'm glad. The rest are not. I think we need to fix that. That does not, however, mean going to war.
War will bring the deaths of many more innocents. When you go to war you condemn those innocents to death, needlessly. That would be stooping to the level of the terrorists. Punishing the civilians for the acts of their neighbors, or their government - isn't that what the terrorists did?
We need to figure out who did it, extract them, put them on trial, and execute them for their crimes. If a mad dog goes wild, you put it to sleep to protect anyone else from being harmed. These individuals, no matter how evil, do not make their neighbors guilty by association. Hatred towards them, their religion, their country, whatever, is wrong. They, and only they, are responsible for their actions. Punish them, and only them, accordingly.
It would be wrong to let them go without punishment, but it would be equally wrong to punish others for their crimes.