Wars in the Middle East will never eliminate the possibility of being sneak attacked by a small group of extremists.
That reminds me of my second tour in Korea, which started 2 months after 9/11. The base I was stationed at tightened security, and I happened to be talking with my 1st shirt, who wanted to know what I thought of the new security measures.
I said that any sufficiently motivated and funded terror cell will be able to get a bomb in, no matter what we do.
Needless to say, the guy flipped out.
I kept pushing to atomize our force concentrations, so any attack would only hurt/kill a small number... instead of their knee-jerk reaction to concentrate our troops into a small location. Which is a big, fat, juicy target to every terrorist cell. They only have to be successful once to cripple operations in the situation.