FORT MEADE (AFP) - Bradley Manning, the US soldier on trial for leaking a massive trove of secret government files to WikiLeaks, arrived at a military tribunal on Tuesday to learn his fate.

Military judge Denise Lind plans to issue a verdict at 1700 GMT. Manning has pleaded guilty to some of the lesser charges against him, and will be sentenced next month.

Lind has to rule on whether Manning is a traitor who spied on his own country and aided America's enemies or a whistleblower who shone a spotlight on what he felt was government misconduct.

If he is convicted of the most serious charge against him, that of aiding the enemy, he could be jailed for life.

And convictions on any or all of the more minor charges against him could add up to a hefty term.

"I am not optimistic," said Nathan Fuller, a spokesman for the Bradley Manning Support Network and one of around 40 protesters who gathered outside the Fort Meade military base where the trial is taking place.

"The judge has sided with the government on several occasions, even allowing the prosecution to change the wording of some charges last week, even after all the evidence had been heard," he said.

Mr Fuller said the verdict had implications reaching beyond Manning's own fate.

"If people cannot make abuses of power known to the public through legitimate news organizations then there is a problem - the government is not going to be transparent on its own," he argued.

Manning was serving as an intelligence analyst in Iraq when he sent Julian Assange's anti-secrecy website WikiLeaks a cache of secret diplomatic cables and classified military reports from the wars in Iraq and Afghanistan.

The 25-year-old has admitted giving the site some 700,000 documents, pleading guilty to 10 lesser charges, including espionage and computer fraud, which could carry a prison sentence of up to 20 years.

But Manning has denied other charges, including the most serious one - that he knowingly helped enemies of the United States, most notably Osama bin Laden and Al-Qaeda.

To find Manning guilty of "aiding the enemy," the judge must be convinced, beyond reasonable doubt, that the soldier knew the documents he leaked could end up in the hands of Al-Qaeda.

Even without being found guilty of this, the other charges could add up to 154 years imprisonment. The sentencing phase of the trial could begin as early as Wednesday.

In closing arguments, defence attorney David Coombs said Manning was no traitor but a "young, naive and good-intentioned" citizen who wanted to encourage public debate about US foreign policy.

In a preliminary hearing in February, Manning read a long letter justifying his actions, in which he spoke of the "bloodlust" exhibited by a US Apache helicopter crew who gunned down a group of Iraqis in Baghdad.

But the prosecution insists Manning recklessly betrayed his uniform and his country by leaking documents he knew Al-Qaeda would see and use.

"He was not a troubled young soul, he was a determined soldier with the knowledge, ability and desire to harm the United States in its war effort," lead prosecutor Major Ashden Fein told the court.

"Your honor, he was not a whistleblower, he was a traitor."