The military judge overseeing the trial of US soldier Bradley Manning over his massive transfer of secret files to WikiLeaks began considering her verdict after closing arguments Friday.

After hearing the final statements at Fort Meade outside Washington, Colonel Denise Lind closed the court. She is expected to give her verdict in the coming days.

At Manning's request, the judge -- and not a jury -- will decide his fate, and he will spend the rest of his life behind bars if convicted of the most serious charges against him.

Manning was a US army private serving as an intelligence analyst in Iraq when he sent anti-secrecy activist Julian Assange's WikiLeaks website a massive trove of diplomatic cables and classified military reports from Iraq and Afghanistan.

Supporters such as Assange argue that if he is convicted it will be a huge blow for the United States' cherished press freedoms, but opponents say Manning betrayed his country and his uniform while aiding America's enemies.

Defense attorney David Coombs told the military court Friday that Manning was no traitor but rather a "young, naive and good-intentioned" whistleblower.

Manning wanted to shed light on America's misdeeds on the battlefield, Coombs argued.

"He was hoping to spark worldwide discussion" through his leaks and was "hoping that things would change based on that information," he said.

As the trial drew to a close, prosecution and defense lawyers clashed over Manning's motives, with the government insisting he had "evil intent" to "aid the enemy."

The 25-year-old intelligence analyst has already admitted to leaking hundreds of thousands of classified diplomatic cables and battlefield intelligence reports to WikiLeaks.

But he has denied other charges against him, including the most serious count that he knowingly helped Osama Bin Laden's global extremist network Al-Qaeda.

Manning's attorney insisted WikiLeaks was "no different than the New York Times" or any other news outlet that seeks to play a watchdog role, and that his client was simply trying to get information to the public.

"In this instance giving something to a legitimate news organization is -- unfortunately or fortunately depending on what side of the fence you are on -- the way we hold our government accountable," Coombs said.

The government's case suggests any leak posted online by news media could be treated as helping America's foes, he argued.

The prosecution, however, portrayed Manning as a reckless "anarchist" who knew Al-Qaeda would see the documents posted online.

"Instead of the American flag, Manning placed his trust in WikiLeaks and Julian Assange," prosecutor Major Ashden Fein said.

But Manning's attorney cited chat logs in which the soldier referred to seeing "awful things" in his intelligence job in Iraq in 2009-2010 and said the reports "belong in the public domain."

His words show he was a whistleblower who cared about his country and wanted Americans and the world to know the truth, the lawyer said, as the slight, bespectacled Manning sat in the court room in a dark blue Army dress uniform.

The defense played a clip from the cockpit video leaked by Manning of a 2007 Apache helicopter attack in Baghdad that killed 12 civilians, including two Reuters news agency employees.

The video shows the Apache opening fire on unarmed men retrieving a wounded Iraqi, with the crew joking afterward.

Coombs said that the Iraqis were "shot like fish in a barrel" and argued: "You have to look at this through the eyes of a young man who cares about human life."

Manning has pleaded guilty to 10 lesser charges, including espionage and computer fraud, that could carry a sentence of up to 20 years in prison.

Prosecutors are trying to prove 12 additional counts, including theft of US property, exceeding authorized access on a government computer and the "aiding the enemy" charge.

Away from the courtroom, Assange and fellow anti-secrecy campaigner Daniel Ellsberg -- best know for the leak of the Vietnam War-era "Pentagon Papers" -- denounced Manning's treatment in a conference call with reporters.

Assange said Manning is "one of the bravest friends that journalists have ever had" and "allegedly the greatest source that ever existed in the history of journalism."

"This is not prosecution merely against a young idealistic intelligence analyst. It is an attempt to redefine how journalism is done in the United States."

Ellsberg drew a parallel between Manning and Edward Snowden, a civilian intelligence technician who leaked details of secret US surveillance programs before going on the run.

Snowden has been criticized at home for seeking asylum in Russia, but Ellsberg said the Fort Meade trial showed why the young leaker was right to flee US justice.

"He doesn't want to be held in a cage like Bradley Manning," he said.