News briefing on the charges against the Blackwater employees
US guards indicted over the 2007 fatal shooting of 17 Iraqis used machine guns and grenade launchers against unarmed civilians, prosecutors have said.
The guards, from the US security firm Blackwater, were contracted to defend US diplomats. The firm says its guards acted in self-defence.
The five men are charged with 14 counts of manslaughter, as well as weapons violations and attempted manslaughter.
A sixth guard has pleaded guilty to killing at least one Iraqi.
The Iraqi government has welcomed the move to hold "criminals accountable".
The killings, which took place in Nisoor Square, Baghdad, have become a central issue in Iraq's relationship with the US and raised questions about the oversight of US contractors operating in war zones.
Witnesses and family members maintain that the shooting on 16 September 2007 was unprovoked.
Although the indictment was made in Washington, the men surrendered at a federal courthouse in Salt Lake City, Utah, the home state of one of the five guards, Donald Ball.
They kept shooting at the first car until it burst into flames
That way the men could argue that the case should be heard in Utah, considered more conservative and pro-gun than Washington, AP said.
"Donald Ball committed no crime," said his lawyer, Steven McCool. "We are confident that any jury will see this for what it is: a politically-motivated prosecution to appease the Iraqi government."
Defence lawyers are expected to file a series of challenges before the guards can even go to trial.
"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," said Khalid Ibrahim, 40, who said his 78-year-old father, Ibrahim Abid, died in the shooting.
"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," he told AP.
The New York Times has previously reported that an FBI investigation had concluded that 14 of the deaths at the busy Baghdad intersection were unjustified.
Young children were among the victims.
As well as Mr Ball, the other men indicted are Dustin Heard, Evan Liberty, Nick Slatten and Paul Slough.
On top of the 14 counts of manslaughter, they face 20 counts of attempted manslaughter, as well as using a machine gun to commit a crime of violence, a charge that carries a 30-year minimum sentence.
A sixth Blackwater employee, Jeremy Ridgeway, agreed to a plea deal in return for testifying against his colleagues, AP reported, adding that the indicted men are decorated military veterans.
Evan Liberty, one of the indicted guards, surrenders in Utah
The problem of private armed guards in Iraq remains unresolved, mainly because they continue to provide security for the many American and other foreign officials in the country.
US law is unclear on whether contractors can be charged in the US or anywhere else for crimes committed overseas.
In October 2007, the Iraqi government approved a draft law revoking the immunity from prosecution that private security contractors enjoyed under Iraqi law.
The US has since put in place new guidelines for security contractors.
Based at a vast ranch complex in North Carolina, Blackwater is one of the main private providers of security within Iraq, and its contract there was extended in April.
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