Maj. Ashden Fein said Manning abused his trust as an intelligence analyst in Iraq and was not the troubled and naive soldier defense attorneys have made him about to be.
Fein displayed a smiling photo of Manning from 2010, about the time he gave sensitive material to WikiLeaks, and said "this is a gleeful, grinning Pfc. Manning" who sent battlefield reports to WikiLeaks, accompanied by the message: "Have a good day."
The 25-year-old has acknowledged giving WikiLeaks hundreds of thousands of battlefield reports, diplomatic cables and videos in late 2009 and early 2010. But he says the information did not harm troops in Afghanistan and Iraq or threaten national security.
The material included video of a 2007 US Apache helicopter attack in Baghdad that killed 11 men, including a Reuters news photographer and his driver. A military investigation concluded the troops reasonably mistook the photography equipment for weapons.
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Fein, the military's lead prosecutor, said Manning had a dog tag with "Humanist" engraved on it, but "the only human Pfc. Manning ever cared about was himself."
"The flag meant nothing to him," Fein said.
Prosecutors have presented evidence that digital copies of some of the documents Manning leaked were found in bin Laden's compound when it was raided and the terrorist leader was killed.
A military judge, not a jury, is hearing the case at Manning's request. Army Col. Denise Lind will deliberate after closing arguments. It's not clear when she will rule.
Federal authorities are looking into whether WikiLeaks founder Julian Assange can also be prosecuted. He has been holed up in the Ecuadorean Embassy in London to avoid extradition to Sweden on sex-crimes allegations.