The 2007 shooting in Baghdad strained Iraq-US relations
Two US men have been charged over the murder of two Afghans after a traffic accident in Kabul last May.
Justin Cannon, 27, and Chris Drotleff, 29, worked for a subsidiary of security firm Xe, formerly known as Blackwater.
The men were sacked after the incident for failing to comply with the terms of their contract.
The charges came on the same day that Xe reached a settlement in a number of separate civil lawsuits over the killings of Iraqi civilians.
The Justice Department said Mr Cannon and Mr Drotleff faced murder charges and could face the death penalty if found guilty.
According to the indictment, two people were killed and one injured as a result of the shooting at an intersection in Kabul.
The accused told the AP news agency in a recent interview that they had been justified in opening fire when a car caused an accident ahead of them, turned and sped towards them.
"I feel comfortable firing my weapon any time I feel my life is in danger. That night, my life was 100% in danger," AP quotes Chris Drotleff as saying.
Earlier on Thursday, Xe welcomed a settlement - for an undisclosed amount - of a number of lawsuits over the killings of Iraqi civilians.
The civil suits accused Blackwater's founder, Erik Prince, of cultivating a climate of recklessness.
The lawsuits sought compensation for deaths and injuries incurred in incidents including the killing of 17 Iraqis in Baghdad's Nisoor Square, in 2007.
Last week a judge dismissed all criminal charges against five Blackwater employees over that incident.