Last week, Manning was found guilty of 20 of the 22 charges of spying and disobeying orders lodged against him, leaving the 25-year-old facing for than a century of confinement.
Legal arguments regarding his eventual sentence are now being thrashed out at Fort Meade military base in Maryland, near the US capital.
Presiding judge Colonel Denise Lind ruled that four groups of charges could be combined for sentencing purposes, reducing the potential maximum term by a third. Manning's sentencing hearing is slated to last until August 23.
The soldier was working as an intelligence analyst near Baghdad when he was arrested more than three years ago and accused of having handed a large quantity of secret military reports and US diplomatic cables to WikiLeaks, the anti-secrecy website founded by Julian Assange.
Manning was cleared of the most serious charge against him, that he had leaked the documents to knowingly help America's enemies, but could still spend the rest of his life behind bars.
The soldier said he passed the documents to WikiLeaks as he wanted to start a public debate about the actions of the US military and diplomats overseas. Government lawyers, however, denounced him as a traitor.


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