I spent the day with Christina Bentley, the UK's first transgender RAF police officer.
US officials said the exchange would boost reconciliation efforts with the Taliban, which is key to Afghanistan's security.
If Hagel is serious about letting trans people serve in the military, he's on the side of science.
The Pentagon is weighing up moving whistleblower Chelsea Manning to a civilian prison. But transphobia and persecution still reign.
Is Secretary of Defense Chuck Hagel just messing with us, or is the Pentagon ready to change its tune on transgender troops?