Five Blackwater security guards were charged today with killing 14 unarmed civilians and wounding 20 others in a 2007 shooting in Baghdad that outraged Iraqis and strained US-Iraqi relations.
In a 35-count indictment, the US Justice Department charged the men with 14 counts of manslaughter, 20 counts of attempt to commit manslaughter and weapons violations.
If convicted, the men face 10 years in prison for each manslaughter charge, plus additional time for other charges.
"The government alleges in the documents unsealed today that at least 34 unarmed Iraqi civilians, including women and children, were killed or injured without justification or provocation by these Blackwater security guards in the shooting at Nisoor Square," said Patrick Rowan, assistant attorney general for national security.
A sixth Blackwater guard pleaded guilty on Friday, the Justice Department said.
An attorney on the team representing the men said they were innocent of all charges.
"They were hired as State Department contractors to protect State government officials," Brent Hatch told reporters in Salt Lake City.
"They did their job as they were contracted to do, as they were required to do, and as the State Department asked them to do it."
The charges came after more than a year of FBI investigations in one of the most high-profile cases remaining before President George W Bush leaves office in January.
The shooting occurred as the private security firm's guards escorted a convoy of US diplomats through Baghdad on September 16th, 2007.
The guards, US military veterans, were responding to a car bombing when shooting erupted in a crowded intersection.
North Carolina-based Blackwater, the largest security contractor in Iraq, has said its guards acted lawfully and in self defense after their motorcade came under fire.
The shooting enraged the Iraqi government, which wanted to put security contractors under Iraqi legal jurisdiction.
Iraqis also were outraged in April when the State Department renewed Blackwater's contract to protect personnel in Baghdad.