US Army officers overseeing Bradley Manning ignored his angry outbursts and signs of mental health problems before he gave secret files to WikiLeaks, his defense lawyer alleged Monday.

Manning, 25, faces up to 90 years behind bars after being convicted of espionage last month over his massive leak of US military intelligence reports and diplomatic cables.

The defense opened its case Monday in the sentencing phase of the trial by questioning officers about how they handled concerns over Manning's mental condition and whether he should have retained his security clearance.

Several officers, including the commander of Manning's brigade from the 10th Mountain Division, Colonel David Miller, said the unit faced a shortage of intelligence analysts but denied sending Manning or other soldiers who were not fit for duty to Iraq.

"In a counterinsurgency fight, you can always use more" intelligence analysts, Miller told the court.

Miller said he was unaware at the time of an incident in Iraq when Manning had flipped over a table and had to be restrained during a counseling session.

The junior intelligence analyst had "a problem getting along with people," according to the head of the brigade's intelligence section, Major Cliff Clausen, citing an account from his deputy.

The company commander, Captain Matthew Freeburg, told the court he was surprised the military had not taken more severe disciplinary action against Manning before he was accused of assaulting another soldier.

The captain demoted Manning over the incident and removed him from the intelligence office, filing paper work that he expected would strip the soldier of his security clearance and possibly expel him from the force.

The defense honed in on an internal military investigation after Manning's leak, which quoted officers describing the head of the soldier's intelligence office and a deputy as "weak" leaders.

"We understood some of the ramifactions of not having the ideal team in there," the brigade's executive officer, Lieutenant Colonel Brian Kerns, said.

Clausen, the head of the brigade's intelligence section, was removed from his position in early 2010 because of alleged difficulties conveying intelligence findings to commanders.

Manning's sentencing hearing is scheduled to last until August 23 and his defense attorney, David Coombs, has said his client will make a statement to the court this week.

At the end of Monday's session the judge, Colonel Denise Lind, ordered the defense to hand over to prosecutors the full report of a sanity board evaluation of Manning's mental state, while editing out the soldier's own statements.

Manning was working as an intelligence analyst near Baghdad when he was arrested more than three years ago over the document dump to WikiLeaks.

Before his trial began, Manning admitted to handing over 700,000 classified documents, including frontline military logs and diplomatic cables, to the anti-secrecy website founded by Julian Assange.

Manning was cleared of the most serious charge against him, that he had knowingly helped America's enemies, but he could still spend the rest of his life in prison.

Manning has said he passed the documents to WikiLeaks to ignite a public debate and reveal the true face of America's wars.

The prosecution has portrayed Manning as a traitor and last week called on witnesses who described the effect of the disclosures, though much of their testimony was behind closed doors as it touched on classified details.

Rear Admiral Kevin Donegan, who was head of operations for US Central Command at the time of the leaks, said troops in Iraq and Afghanistan were ordered to warn people and villages exposed in the files that they were at risk.

Troops told the sources identified in the published documents that they were "potentially in jeopardy and some of them in danger of retaliation from the enemy," the Navy admiral said.