Preview: Bret Interviews Outgoing NSA Director General Keith Alexander

BAIER: Former President Jimmy Carter saying he writes letters instead of sending e-mails because he's worried that you're listen -- you're reading his e-mails.

ALEXANDER:  Well, we're not.  So he can now go back to writing e-mails.  The reality is, we don't do that.  And if we did, it would be illegal and we'd be found, uh, I think accoun -- held accountable and responsible.  Look at all the folks that have looked at what we're doing, from the president's review group to Congress to the courts to the DNI, DOD, Justice.  Everybody reviews what we do to see if anybody is doing anything illegal like you suggest.  No one has found anything, zero, except for in 12 cases where people did that and we had already reported those.