Five guards from the private US security firm Blackwater have been charged with killing 14 unarmed civilians and wounding 20 others in a shooting in Baghdad last year.
United States officials say the 35 charges include manslaughter, attempt to commit manslaughter and weapons violations.
A sixth Blackwater guard pleaded guilty last week.
The shooting by the security firm guards as they escorted a convoy of US diplomats through Baghdad more than a year ago ignited a deep outcry in Iraq and led US officials to tighten controls on guards and contractors.