"Bad news for me: Military continues to make me cut my hair to male standards. I'm gonna fight in court," Manning said in a tweet.
— Chelsea Manning (@xychelsea) September 18, 2015
Manning, formerly known as "Bradley," came out as transgender in August 2013 after she was convicted of violating the Espionage Act by leaking classified information to WikiLeaks. She is serving a 35-year prison sentence at Fort Leavenworth, Kansas
"Even though the military agrees that allowing Chelsea to grow her hair is a critical part of her treatment plan, they continue to deny her basic human and constitutional rights," said Chase Strangio, an attorney for the ACLU's LGBT Project.
In September 2014, Manning sued the US military for denying hormone treatment that would enable her to transition to a woman. She won that case in February.
"When we filed our lawsuit a year ago," Strangio said, "Chelsea had already waited more than a year for even minimal care to treat her gender dysphoria. We are confident that this decision will be overturned by the court but saddened that Chelsea’s treatment continues to be needlessly impeded."
Gender dysphoria is a condition in which the gender one identifies with does not line up with the one assigned at birth.
On Thursday, Manning began three weeks of restricted activities – the punishment the Army imposed for her conviction last month of charges of prison misconduct.
Strangio said Manning will "carry these infractions through her parole and clemency process and will be held longer in the more restrictive custody where she is now incarcerated."
Manning had expected to be moved to minimum custody in February, but now it could be years before that happens.