Bradley Manning's lawyers made their closing statements yesterday, in the preliminary hearing for the Army intelligence analyst accused of creating the biggest national security leak in US history.

A military prosecutor summed up by saying Pte Manning defied the nation's trust by pulling more than 700,000 documents from a supposedly secure computer network and giving national secrets to the WikiLeaks website. But Pte Manning's defence lawyer argued that the Army failed the 19-year-old and is piling on charges in an attempt to force him into pleading guilty.

An investigating officer at Fort Meade military base in Maryland must now advise if he should face court-martial on 22 charges, including aiding the enemy. He could be jailed for life if found guilty.

It has been nearly 19 months since Pte Manning was charged with giving WikiLeaks a trove of classified data, including hundreds of thousands of State Department diplomatic cables. The reason he allegedly gave, in chats with a confidant who turned him in: "I want people to see the truth."

His lawyers say Pte Manning was a troubled man who should not have had access to classified material, let alone served in Iraq. They argue that security at his workplace was weak and that the published material did little or no harm to national security.