FORT MEADE, Md. — Lawyers for the Army private who leaked a trove of classified government documents urged a judge Monday to dismiss a charge that he aided the enemy, saying prosecutors failed to prove Pfc. Bradley Manning intended for the information to fall into enemy hands.

The charge is the most serious and carries the most severe punishment — life in prison — in the military's case against Manning, who has acknowledged sending hundreds of thousands of documents to the anti-secrecy website WikiLeaks.

The trial of the 25-year-old Oklahoma native is drawing to a close on a military base outside Baltimore and a judge hearing the government's case is weighing whether to dismiss that charge and several lesser counts. Manning has pleaded guilty to reduced versions of some charges. He faces up to 20 years in prison for those offenses.

On the main charge, Manning's lawyer, David Coombs, argued that Manning could have sold the documents, which included battlefield reports and State Department diplomatic cables, or given them directly to the enemy. Instead, he gave them to WikiLeaks in an attempt to "spark reform" and provoke debate. Manning had no way of knowing whether Al-Qaida would access the secret-spilling website and said a 2008 counterintelligence report showed the government itself didn't know much about the site, Coombs said.

The title of that report — "Wikileaks.org -- An Online Reference to Foreign Intelligence, Services, Insurgents, or Terrorist Groups?" and its inclusion of a question mark suggested a great deal of government uncertainty about the nature of the site, Coombs said.

"What better proof that Pfc. Manning wouldn't know than that the United States Army doesn't know if the enemy goes to WikiLeaks," Coombs said.

Coombs also argued that the charge requires Manning had "evil intent" in leaking the documents, which he said the government did not prove.

The government charged Manning with indirectly aiding the enemy for causing intelligence to be published online, knowing it would be seen by al-Qaida members. Prosecutors produced evidence that al-Qaida leader Osama bin Laden obtained digital copies of some of the leaked documents WikiLeaks published. They also charged Manning with espionage, computer fraud and theft.

Prosecutors say the former intelligence analyst had received sophisticated computer training and would have understood that al-Qaida had an online presence and could easily access the information.

"Pfc. Manning is distinct from an infantryman or a truck driver because he had training... this was his job," said Capt. Angel Overgaard, a military prosecutor.

The defense rested its case last week. Col. Denise Lind, the military judge, said she would rule Thursday on whether to acquit Manning of the aiding the enemy charge and several lesser counts.

Manning chose a judge, rather than jury for his court martial, which is drawing to a close at the Army's Fort Meade base.

Hours before Monday's hearing began, some two dozen supporters stood in 90-plus-degree temperatures outside the entrance to the military base holding signs that read "Release Bradley Manning," ''We love Bradley." Inside the courtroom, supporters — many of whom consider him a whistleblower — wore black T-shirts imprinted with the word "truth." Manning sat through the courtroom arguments, pen in hand and appeared to listen intently as the lawyers spoke.

Manning has acknowledged giving the anti-secrecy group hundreds of thousands of Iraq and Afghanistan battlefield reports and State Department diplomatic cables, along with battlefield videos and other documents. The material included video of a 2007 U.S. Apache helicopter attack in Baghdad that killed 11 people, including a Reuters news photographer and his driver. A military investigation found troops mistook the camera equipment for weapons.

He downloaded the material in late 2009 and early 2010 from a classified government computer network while working as an intelligence analyst in Iraq. WikiLeaks posted much of the material on its website.

The judge also heard arguments on whether to dismiss a charge that accused Manning of using unauthorized software on his computer desktop to download the documents. Manning's lawyers say he was authorized to access the information that he downloaded.