Soldier Chelsea Manning, who is serving 35 years in a military prison for leaking classified documents to WikiLeaks, was found guilty on Tuesday of violating jail rules and given three weeks of recreation curbs, the American Civil Liberties Union said.
The former intelligence analyst was convicted in 2013 of providing more than 700,000 documents, videos, diplomatic cables and battlefield accounts to WikiLeaks, in the biggest breach of classified materials in U.S. history.
She was facing possible solitary confinement for the infractions at the military prison at Fort Leavenworth, Kansas.
"Chelsea's ridiculous convictions today will not silence her," her attorney Nancy Hollander said on Twitter. "And we will fight even harder in her appeal to overturn all her convictions."
Manning, who was born a man but identifies as a woman, faced a disciplinary board on Tuesday on charges of attempted disrespect and possession of prohibited books and magazines during administrative segregation, Hollander said, among other charges.
These included misuse of medicine, pertaining to expired toothpaste, and disorderly conduct, for pushing food onto the floor.
Manning was found guilty of all charges and sentenced to 21 days without access to recreation, including the gym, library and outdoors.
She had faced a maximum penalty of indefinite solitary confinement.
Items confiscated from Manning included a Vanity Fair magazine whose cover featured former Olympic athlete Bruce Jenner, who is transitioning to life as a woman.
Manning, known as Bradley Manning before a name change after her arrest, had some books and novels on gay and transgender themes, Hollander said last week.
Manning's supporters on Tuesday delivered a petition with more than 100,000 signatures to Army officials in Washington, accusing them of trying to silence her and urging them to drop the charges, according to the website Freechelsea.com.
The U.S. Army did not immediately return a telephone call seeking comment.
Manning worked as an intelligence analyst in Baghdad when she gave WikiLeaks the government material.
Last year, the Pentagon said the U.S. Army would provide gender identity treatment for Manning. Hollander said the Army was providing hormone treatment for her.