[proofofconcept]

The form of the argument depends on the two not meshing. The Snowden leaks provide evidence of the former case. The contradiction between that and the latter case suggests that perhaps the NSA is not being completely forthright with the public about the scope and purpose of its domestic surveillance. It's not that hard of an argument to follow, and given how tight-lipped the executive branch has been so far it's a pretty persuasive one.