The biggest announcement out of yesterday's meeting between Presidents Obama and Nazarbayev was that Kazakhstan would allow overflight rights of planes going over the North Pole, then south over Russia and then through Kazakhstan and then Uzbekistan or Kyrgyzstan/Tajikistan. I spoke to Andrew Kuchins, a CSIS scholar who has interviewed many American, Russian and Uzbek officials about the Northern Distribution Network for a CSIS project. He pointed out that Pentagon officials were never especially interested in this polar route, that it was originally proposed by the Russians as a concrete "deliverable" that Obama and Medvedev could announce during their meeting in Moscow last July. The Pentagon would rather get permission to transit lethal cargo over its existing routes.
And yet, negotiating that extra route shortly became the top priority in the U.S.'s relationship with Kazakhstan; as one State Department official told me, "the NDN trumps everything." And it was the main achievement of the one-to-one between Obama and Nazarbayev. 
My takeaway: There is an interesting behind-the-scenes story to tell about how an afterthought at the Pentagon became the top priority at the White House...