Their goal is to maximize destruction given the resources they have. If they had a button that instantly destroy the US, of course they would press it. But the fact is that they don't have such a button; they have very limited resources. Their most efficient use of resources is to make random, very visible and violent attacks and hope that our responses do even more damage.
Huh? Just because they don't have said resources to kill everyone in the U.S. doesn't mean it's not their ultimate goal... No one can say whether or not they could eventually acquire those resources via rogue states.
UBL specifically stated that jihadist should NOT differentiate between Military/Government and civillians.
