Speaking inside the Ecuadorian embassy in London, WikiLeaks founder Julian Assange said the conviction of soldier Bradley Manning on espionage charges set a "dangerous precedent".
Pte Manning, who has admitted leaking confidential information to WikiLeaks, was convicted of 19 charges.
Mr Assange said the only victim in the case had been the US government's "wounded pride", adding that Manning's disclosures had helped spark the Arab Spring.
Manning's sentencing will begin tomorrow but Mr Assange said there were two appeals within the US justice system as well as the Supreme Court.
More top news
Colder but clear this evening
Two teenagers found dead at the foot of a sheer drop at Huntcliff have been named as 17-year-olds Alex Yeoman and Harry Watson.
Violet Grace Youens died in hospital a day after she was struck in a suspected hit and run as she walked with her grandmother in Merseyside.