(CNN) The U.S. Army has agreed to provide hormone therapy for Chelsea Manning, the soldier serving a 35-year prison sentence for leaking a huge trove of classified documents.

The prisoner formerly known as Bradley Manning, and once held to be male, said in August 2013 , the day after her court sentencing, that she is female. Just over a year later, it emerged that she had filed a lawsuit in federal court claiming she "has been denied access to medically necessary treatment" for her gender disorder.

The commandant of the Fort Leavenworth Disciplinary Barracks in Kansas, where Manning is serving her sentence, issued a memo on February 5 authorizing the addition of hormone therapy to Manning's treatment, USA Today reported Thursday

The memo cited a recommendation that the therapy was "medically appropriate and necessary."

The news was welcomed by Manning's legal counsel in the lawsuit.

"We are thrilled for Chelsea that the government has finally agreed to initiate hormone therapy as part of her treatment plan," said Chase Strangio, an attorney with the American Civil Liberties Union. "This is an important first step in Chelsea's treatment regimen and one that is in line with the recommendations of all of her doctors and the basic requirements of the Eighth Amendment."

Not allowed to grow hair

But Strangio said that the approval of the therapy was only a partial victory.

"The military continues to refuse to let Chelsea grow her hair like other female prisoners, a critical part of her treatment plan that has been recognized by her doctors," he said.

Also, the delay in getting the hormone treatment "came with a significant cost to Chelsea and her mental health," Strangio said.

At the time of her 2013 announcement that she planned to live as a woman, Manning asked for support and said she wanted to begin hormone therapy as soon as possible.

Manning said she was diagnosed in 2010 with gender dysphoria, which her lawyers describe as "the medical diagnosis given to individuals whose gender identity -- their innate sense of being male or female -- differs from the sex they were assigned at birth, causing clinically significant distress."

A Kansas judge in April granted the former Army intelligence analyst's request to formally be known as Chelsea Elizabeth Manning.