The only scenarios I'm 'coming up with' are the ones that have been reported. I don't know who the NSA is listening to, and neither do you. But if you believe they are only listening to AQ and people communicating with AQ, I've got some real, real nice land you might be interested in...
If you, Lugsoul were CIC and if you had credible reports that 12 nukes were about to go off in 12 cities at the residence of 12 terrorists, would waste valuable time getting a warrant or would you act immediately against the terrorists?