The Los Angeles Times reports: Army Pfc. Bradley Manning pleaded guilty Thursday to ten charges that he illegally acquired and transferred highly classified U.S. materials later published by WikiLeaks, saying he was motivated by a U.S foreign policy that “became obsessed with killing and capturing people rather than cooperating” with other governments.

“I felt we were risking so much for people who seemed unwilling to cooperate with us due to the mistrust and hatred on both sides,” Manning said, reading a 35-page, hand-written statement describing his angst over the wars in Iraq and Afghanistan.

“I began to become depressed with the situation we had become mired in year after year,” he added.

In a plea arrangement with military prosecutors, Manning agreed to serve a 20-year prison sentence in exchange for pleading guilty to ten lesser charges. But he also pleaded not guilty to 12 more serious criminal charges, including espionage, and will face a court-martial in June. If convicted, he could face a life sentence.

Manning, now 25, was posted as a low-level intelligence analyst at a base outside Baghdad until his arrest three years ago.

He said was angered at one point when 15 Iraqis were arrested as protesters, yet none were known terrorists or involved in anti-government activities. When he complained to his superiors, he said, “no one wanted to do anything about it.”

Manning said he eagerly logged into WikiLeaks’ chat rooms and submitted material to the organization because he was impressed with their efforts to expose inner workings of U.S. military and diplomatic operations.

“I routinely monitored their website,” he said. “It helped me pass the time and keep motivated throughout my deployment.”