Bradley Manning, the Army private who sent hundreds of thousands of secret U.S. government documents to WikiLeaks, was found not guilty on Tuesday of the most serious charge against him -- aiding the enemy -- but guilty of several other charges at a military trial in Fort Meade, Md.

Conviction on aiding the enemy carried a possible sentence of life in prison without parole.

Col. Denise Lind, the military judge in the case, made the ruling. Manning had requested that a judge, not a jury, determine the verdict against him.

Lind found Manning guilty of 19 of 21 charges, including five counts of theft, six counts of espionage, a computer fraud charge and other military infractions.

Manning's sentencing hearing is set to begin Wednesday. He still faces a potential 128 years in prison if he receives the maximum sentence for the charges on which he was convicted.

RIEDER COLUMN: Sensible decision made in Manning case

In his closing argument last week, military prosecutor Maj. Ashden Fein, told the court Manning was a traitor who joined the Army to steal government documents, turn them over to the anti-secrecy organization and enjoy adulation as a whistle blower.

Manning's lawyer, David Coombs, portrayed him as a soldier troubled by what he saw while deployed to Iraq and struggling as a gay man to serve before the repeal of Don't Ask, Don't Tell, the policy that resulted in more than 14,000 gay troops being discharged.

Manning, 25, has acknowledged giving WikiLeaks some 700,000 battlefield reports, diplomatic cables and videos. But he says he didn't believe the information would harm troops in Afghanistan and Iraq or threaten national security.

ANALYSIS: Manning case redefined what it means to be a traitor

The prosecution argued that Manning knew a- Qaeda terrorists could benefit from the leaks. Some of the information turned up in the search of Osama bin Laden's compound in Pakistan, they said.

Manning pleaded guilty in February to charges that he had misused classified information. Those charges carry a maximum term of 20 years in prison.

Analysts say the government had to clear a higher hurdle in proving that Manning intentionally aided the enemy. They would have to prove that he could reasonably conclude that release of the information would find its way into enemy hands after he turned it over to WikiLeaks.

"They did not prove beyond a reasonable doubt that he had a specific intent to aid or assist the enemy," said Phil Cave, a former military lawyer now in private practice.

Manning was a low-level intelligence analyst, working at a forward operating base in Iraq when he gained access to the files. He used his computer savvy to gain access to sensitive government documents and communications.

The material he released included footage of a U.S. Army helicopter attack in Iraq in 2007 that killed at least nine men, including a Reuters journalist. Other documents revealed tepid U.S. support for the government in Tunisia. Manning's supporters say that helped bring about the revolution there that sparked the Arab Spring movement.

The verdict and sentence will be reviewed by the commander of the Military District of Washington. A hearing on his sentence is set to begin Wednesday.

Manning has been held in military jails since his arrest in 2010.

Contributing: Jim Michaels and Associated Press