Prosecutors in Army Pfc. Bradley Manning's court-martial are calling a strategic list of witnesses to try and prove that Manning was trained to handle sensitive information and deliberately defied orders to protect it.
Manning pleaded guilty in February to 10 charges relating to 700,000 documents leaked to the anti-secrecy website WikiLeaks.
The US military and the Obama administration are now seeking a greater charge of aiding the enemy, which could carry a life sentence.
Manning admitted to sending the materials to WikiLeaks but maintains he did not believe the information would harm the US and his fellow soldiers.
The defense is focused on arguing that the young soldier never displayed any anti-American sentiment or any desire to harm the nation or its military.
Prosecutors, meanwhile, are calling a list of witnesses to testify that Manning was highly trained in how to handle intelligence and a whiz at computers.
Jihrleah Showman, an Army specialist who was Manning’s team leader, testified that Manning was known among his fellow soldiers as someone who could easily get around secret computer passwords to retrieve sensitive information.
"He indicated to me he was very fluent in computers, that he spoke their language, and that there was nothing he could not do on a computer," she said.
On Tuesday, the court heard about an incident where Manning was disciplined for publishing a YouTube video for his family and friends where he disclosed what he was learning.
Manning's unit supervisor, retired Sgt. 1st Class Brian Madrid, testified that he trained Manning to be come a 35 Fox, a category of army intelligence analyst with clearance to draw data from secret military databases.
Madrid testified that while Manning was a student he had to undergo "corrective training" as a punishment for releasing the YouTube video where he used the phrase "top secret".
Manning was required to present a PowerPoint to other soldiers about the dangers of disclosing secret information.
"Use common sense, we have many enemies and have a free and open society," the presentation said.
Manning, 25, was first arrested in Iraq three years ago on charges that he sent the classified material to the online anti-secrecy website WikiLeaks.
The materials that Manning admitted to leaking to WikiLeaks included diplomatic cables, war logs from Iraq and Afghanistan and video footage of a 2007 US helicopter attack that killed civilians Baghdad, reports the Baltimore Sun.
WikiLeaks has never confirmed nor denied Manning’s involvement in the leaked documents.
The information "has great value to our adversaries and in particular our enemies," Army prosecutor Capt. Joe Morrow said during the government's opening argument at Fort Meade.
"This, your honor, this is a case about a soldier who systematically harvested hundreds of thousands of documents from classified databases and then dumped that information on to the Internet into the hands of the enemy," Morrow said.
The Obama administration has said the more than 700,000 leaked documents put the US at risk and threatened valuable military and diplomatic sources and strained America's relations abroad.
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