Chelsea Manning, the imprisoned soldier at the centre of the WikiLeaks scandal, faces 14 days solitary confinement after an attempt at taking her own life in July.
The news was broken by the non-for-profit organisation Fight for the Future on Friday, and confirmed by her lawyer, Chase Strangio, and Chelsea herself on Twitter.
Manning, who is serving 35 years in prison for espionage after releasing government documents to WikiLeaks, will serve seven days in solitary confinement with another seven suspended.
In a statement issued by Fight for the Future, Manning said will be allowed to appeal the sentence.
Manning confirmed there was no date set for the punishment to begin, and said: "I am feeling hurt. I am feeling lonely. I am embarrassed by the decision. I don't know how to explain it."
The 28-year-old faced three separate charges. The first two charges of resisting the force cell move team and conduct which threatens, relate to Manning's suicide attempt. The third charge of being in possession of prohibited property relates to a book, Hacker, Hoaxer, Whistleblower, Spy by Gabriella Coleman, which was found in Manning's cell.
The American Civil Liberties Union (ACLU) said she would be the first trans inmate to receive treatment of this kind in prison, though similar cases have been brought before US courts, including that of Ashley Diamond.
In the UK, there have been several high-profile cases of transwomen serving sentences in male prisons in recent years.
Shortly after the death of Vicky Thompson, 21, by suicide at Armley prison in Leeds last year, the UK government announced a review into the care and treatment of transgender prisoners.