Its hard to imagine the United States being able to even afford another medium scale war like the Iraq war and much less likely to acquire the necessary political support for any sort of preemptive assault. I think anything shy of a nuclear attack on Israel by Iran or on South Korea by North Korea, America will not be involved in any "war" for the next 15-20 years. What does the LRC think tank think?
On a side note, Al-Qaeda seems to be all but defeated. From what I've read, Al-Qaeda is probably less funded, has less combat training, and has fewer members than your local running club.