David Sanger's story in today's NYT about the Obama administration's unsuccessful back-channel efforts to get Iran to agree to a nuclear deal finishes with this telling--and not unrelated--detail:

Mr. Obama is reported to have sent Ayatollah Khamenei two private letters this year, but he received only one response, mostly a litany of past grievances.

And now comes the news that Iran is charging those three American hikers with espionage. At this point, it's almost impossible to see how Obama meets his self-imposed end-of-the-year deadline for diplomatic progress with Iran.