In a New York Times story on Pakistan and Afghanistan, David Sanger writes:

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.