Bradley Manning's letter, entitled The Next Stage of My Life, was signed with a handwritten signature in the name of Chelsea Manning.
The letter was broadcast on NBC's Today show as Manning's lawyer revealed the soldier's desire to live life as a woman.
More top news
Phillip Schofield has revealed that an eccentric fan who wanted to marry him arranged a wedding - leaving him with the bill.
Very young children are just as likely to spread the disease as they are to catch it, a health chief warned.
Anger at the verdict in the shooting of black teenager Michael Brown has left the US deeply divided during its celebration of togetherness.