The US has investigated a number of cases of alleged killings in Iraq
Three US soldiers have been charged with murder over the deaths of four Iraqis in Baghdad, the US army says.
The victims were blindfolded, shot and dumped in a canal in April 2007.
Sgt John Hatley, Sgt 1st Class Joseph Mayo, and Sgt Michael Leahy Jr have been charged with premeditated murder, conspiracy to commit premeditated murder and obstruction of justice.
It was alleged that the killings were in retribution for casualties sustained by the soldiers' unit.
A pre-trial hearing will determine whether a court martial will be held, a spokesman for the Joint Multinational Training Command in Grafenwoeher, Germany, said.
Four other soldiers were charged with conspiracy over the same incident last week, AP reported.
Sgt Hatley and Sgt Leahy, formerly of 1st Battalion, 18th Infantry Regiment, were also charged with one count each of premeditated murder and conspiracy to commit premeditated murder in relation to a death near Baghdad in January 2007.
Sgt Leahy was also charged with being an accessory after the fact, an army statement said, but it gave no further details.
US troops in Iraq have faced several accusations of unlawfully killing civilians and abusing detainees, prompting inquiries into their conduct.
In the largest case, eight marines were originally charged in connection with the deaths of 24 Iraqi civilians in the town of Haditha, in Anbar province on 19 November 2005.
Only one marine - Sgt Frank Wuterich - still faces charges in relation to the incident. He will be tried on nine counts of voluntary manslaughter later this year.