Chelsea Manning, who spent more than three years in prison for leaking US military secrets to WikiLeaks, was jailed again Friday for refusing to testify in a grand jury investigation targeting the anti-secrecy group. US District Judge Claude Hilton ruled Manning in contempt of court and ordered her held not as punishment but to force her testimony in the secret case, according to a spokesman for the US attorney in the Alexandria, Virginia federal court. In a statement, Manning said she had "ethical" objections to the grand jury system and had answered all questions about her involvement with WikiLeaks years ago. Manning, 31, a transgender woman previously known as Bradley Manning, was a military intelligence analyst. She delivered more than 700,000 classified documents related to the wars in Iraq and Afghanistan into WikiLeaks's hands. The documents exposed cover-ups of possible war crimes and revealed internal US communications about other countries.