Was it the Taliban's intention to invade the US?
Can an attack be called a war when the only intention is to inflict damage and death, without invading and occupying a country and when the perpetrators don't do that in the name of a country?

OTOH, by calling it a war, all kinds of actions are set up: sending an army, openly, bombing a country....The problem is, because the enemy really are terrorists, you can't talk to them to settle a peace treaty, as it happens when a war is no more pursued.

Terrorists are able to hide, wait for a more appropriate moment to strike.
They need to be intercepted by agents who also are hiding (false names, etc) and can also strike at the best moment.

I'm convinced historians, by comparing with other wars and other acts of terrorism, will also argue the reason why president Bush has not been able to succeed, was because he used the logic of war while he should have answered to a terrorist attack.