"A senior U.S. official told NBC News that the U.S. government had sought to have both Griner and Whelan released as part of a swap with the Kremlin, which wanted the return of Viktor Bout, a Russian arms dealer who has served 11 years of a 25-year sentence in the U.S. But the official said Russia has treated Whelan differently because he is an accused spy, and that the Kremlin gave the White House the choice of either Griner or Whelan — or none."