Bradley Manning was a traitor on a mission to betray his country's trust as an intelligence analyst in Iraq, according to the prosecution at his military trial in the United States.
Manning, 25, aimed to find and reveal US government secrets to a group of anarchists, then bask in the glory as a whistleblower, said prosecutor Major Ashden Fein.
In his closing arguments, Mr Fein said the US soldier betrayed his country's trust and gave classified information to the anti-secrecy website WikiLeaks, knowing the material would be seen by al Qaida.
"WikiLeaks was merely the platform which Pfc Manning used to ensure all the information was available for the world, including enemies of the United States," said Mr Fein.
Manning is charged with 21 offences including aiding the enemy, which carries a possible sentence of life in prison.
Manning has acknowledged giving WikiLeaks hundreds of thousands of battlefield reports, diplomatic cables and videos in late 2009 and early 2010. But his lawyers insist he did not believe the information would harm troops in Afghanistan and Iraq or threaten national security.
Prosecutors must prove Manning knew al Qaida would see the material to get a conviction on the most serious charge of aiding the enemy. They presented evidence Manning knew "the enemy" in general used the internet, and that leakers with evil intent might use WikiLeaks to spill secrets.
As court was adjourned for the day, a man in the public gallery said: "You're a hero, Bradley, as far as I'm concerned." Several others murmured support for Manning in what became a loud buzz.
The judge angrily shouted: "Gallery, that's enough."