First, we clobber anyone connected with the terrorist attacks. Make it clear, you mess with us, you will hurt bad.
Then, we reformulate a foreign policy that has, as one plank, that we don't dick around with other governments if they don't dick around with us. (We need spy organizations to keep tabs on what others may be trying to do, but we keep our noses out of other peoples' business.) Keep reasonable tabs on national interests like oil (but, dammit, develop energy sources to free us from the damn middle east oil pool! Once we do that, we pull out of the region and tell them all to go to hell.)
(To a lesser extent, same policy with our friends and allies. Our REAL friends and allies, none of this Saudi "money under the table to bin Laden" friendliness. Someone attacks England, we help them.)
Cripes, I'm sounding half like Pat Buchannan. OMG.