Alleged Wikileaks source Bradley Manning communicated directly with the website's founder Julian Assange, prosecutors argued on the fifth day of his pre-trial hearing.
But Private Manning's lawyer said the US soldier should never have been given access to the classified material.
They also argued workplace security at his Baghdad post was inadequate.
The hearing, which began on Friday, is to determine whether the 24-year-old will be court-martialed.
Pte Manning faces 22 charges of distributing state secrets and aiding the enemy. If convicted, he could face life in prison.
The prosecution was due to call six final witnesses before proceeding to the defence and closing arguments.
The prosecution said on Tuesday that evidence from Pte Manning's computers and storage devices suggested he had been in contact with Mr Assange the founder of Wikileaks, the anti-secrecy website.
Digital crimes investigator David Shaver told the court that he discovered a data card owned by Pte Manning, which held 500,000 classified battlefield reports as well as contact details for Julian Assange.
"This is possibly one of the more significant documents of our time, removing the fog of war and revealing the true nature of 21st century asymmetric warfare. Have a good day," Pte Manning wrote in one text file, according to Mr Shaver.
Pte Manning's former supervisor Jihrleah Showman also testified by telephone, and said she had repeatedly recommended he should not be deployed to Iraq.
She said she was "furious" when she discovered he would be sent to Iraq.
"I was trying to determine if he had - not that I'm a medical professional - if he had some psychotic issues," Ms Showman said.
Ms Showman described a clash with Pte Manning during which the intelligence analyst allegedly punched her in the face.
"He attacked, he punched me in the face, unprovoked, and displayed an uncontrollable behaviour that was deemed untrustworthy at the time," she said.
She added that she had no indication his condition was related to any gender identity disorder - an issue that the defence team have previously said Pte Manning struggled with.
In other arguments, prosecutors cited a conversation between Pte Manning and mathematician Eric Schmiedl in which the accused allegedly boasted about leaking a 2007 video of a helicopter attack to Wikileaks.
"I was the source of the 12 July, 2007, video from the Apache Weapons Team which killed the two journalists and injured two kids," Pte Manning said, according to the prosecution.
On Monday, presiding officer Paul Almanza held two closed sessions while witnesses were testifying on the classified material.
The move outraged supporters of Pte Manning, who believed the session should have been open to the public, since the documents were already in the public domain.