Five decorated war veterans face criminal charges over the shooting of Iraqi civilians.
A sixth Blackwater guard had already pleaded guilty to charges on December 5.
If convicted, the men face 10 years in prison for each manslaughter charge, plus additional sentences for other charges.
The shooting by Blackwater’s guards as they escorted a convoy of US diplomats through Baghdad on September 16 2007, angered Iraqis and led US officials to tighten controls on private security firms.
The shooting also enraged the Iraqi government, which wanted to put security contractors under Iraqi legal jurisdiction.
The five men’s identities and the nature of the charges against them had been kept secret for more than a year, but were also released on Sunday.
They were named as Evan Liberty and Donald Ball, both 26-year-old former marines; Dustin Heard, a 27-year-old ex-marine; Nick Slatten, 25, an ex-army sergeant; and Paul Slough, a 29-year-old army veteran.
Paul Cassell, a Utah attorney on the defence team, said as the guards were being heard: “We think it’s pure and simple a case of self-defence … Tragically people did die.”
Khalid Ibrahim, a 40-year-old electrician who said his 78-year-old father, Ibrahim Abid, died in the shooting, said: “The killers must pay for their crime against innocent civilians.
“Justice must be achieved so that we can have rest from the agony we are living in. We know that the conviction of the people behind the shooting will not bring my father to life, but we will have peace in our minds and hearts.”
An Iraqi government spokesman said that they believed that the attack was tantamount to deliberate murder.
Ali Al-Dabbagh told Al Jazeera that Baghdad would maintain the victims’ right to a fair trial and would not accept anything less than “normal standards available in such cases”.
The Blackwater guards are decorated war veterans who were contracted to protect US diplomats in Iraq.
FBI investigators found in late 2007 that most of the deaths had been unjustified and the incident created a furore about the perceived ability of private guards to act with impunity in Iraq.
|FBI investigators found that most of the 17 deaths in Baghdad had been unjustified|
Blackwater said that the guards were returning fire after their convoy was shot at in al-Nisoor Square.
The head of Blackwater appeared before the US congress shortly after the incident, saying that the men acted responsibly.
The case has also been complicated because, at the time of the attack, private contractors like Blackwater operated without any clear legal oversight and it could be argued they did not have to answer either to Iraqi or US laws.
Under the deal Blackwater had with the US government, it was allowed to repair the vehicles involved in the attack before investigators saw them, taking away key forensic evidence.