US Army Private First Class Bradley Manning (C) departs the courthouse at Ft. Meade, Maryland July 30, 2013. [Photo/Agencies]

"Most journalists are not in the business of publishing classified documents, they're in the business of reporting the news, which is not the same thing," he said. "This is not good news for journalism, but it's not the end of the world, either."

Glenn Greenwald, the journalist, commentator and former civil rights lawyer who first reported Edward Snowden's leaks of National Security Agency surveillance programs, said Manning's acquittal on the charge of aiding the enemy represented a "tiny sliver of justice."

But WikiLeaks founder Julian Assange, whose website exposed Manning's spilled US secrets to the world, saw nothing to cheer in the mixed verdict.

"It is a dangerous precedent and an example of national security extremism," he told reporters at the Ecuadorean Embassy in London, which is sheltering him. "This has never been a fair trial."

To prove aiding the enemy, prosecutors had to show Manning had "actual knowledge" the material he leaked would be seen by al-Qaida and that he had "general evil intent." They presented evidence the material fell into the hands of the terrorist group and its former leader, Osama bin Laden, but struggled to prove their assertion that Manning was an anarchist computer hacker and attention-seeking traitor.

Coombs said during trial that Manning had no way of knowing whether al-Qaida would access the secret-spilling website and a 2008 counterintelligence report showed the government itself did not know much about WikiLeaks at the time.

An aiding the enemy charge for someone who didn't directly give an adversary information is extremely rare, and prosecutors had to cite a Civil War-era court-martial of a Union soldier when they brought the charge against Manning.