And I wasn't being flippant.
I've read stories (possibly fiction) that said the US must bury its computers to keep (Former) Soviet spy satellites from reading their hard drives. The same type of satellites that can monitor 50,000 phone calls per minute searching for keywords etc. And if these stories are true, then they can also count the money in your wallet thanks to the magnetic strip in the bills.
That said, there is no reason we can't implant a chip in these suspected terrorists to track their whereabouts and travels abroad and it the US.
I know the "Suspected" part is a problem.