Would terrorists risk more attacks?

It may sound like a stupid question but if terrorists did attack again they would be giving the US permission to do almost anything it wanted. The same goes for the UK, i mean many people in this country are anti-bush now but if we were to have a spectacular attack here i could see this changing over night as revenge sets in. My question is what could we expect to happen if another 9/11 type of attack were to happen in either the US or UK, i am particularly interested in what the US reaction would be to a an attack in this country as we are close allies at the mo.

Ever seen a dead terrorist that cared what the US did? The guys on the planes who took out the WTC probably don't give a flying flip do they? It won't matter what the US does, you can't beat a birth rate and if you could we wouldn't be being over run with Mexicans now.