U.S. Army Private Bradley Manning says he gave hundreds of thousands of classified documents to the WikiLeaks website to start a public debate about the role of the military in Iraq and Afghanistan.
Manning pleaded guilty Thursday in a pre-trial hearing to 10 of 22 charges in the biggest leak of government secrets in U.S. history.
Military judge Colonel Denise Lind accepted his guilty pleas, which could send him to prison for 20 years.
The Army private pleaded not guilty to the most serious charge - aiding the enemy, which carries a sentence of life in prison.
U.S. government secrets exposed by WikiLeaks starting in 2010 stunned diplomats around the world and outraged officials, who said the leaks damaged national security and put American lives in danger.
Manning's court martial is to begin June 3.