The harshest penalty Staff Sergeant Frank Wuterich, 31, now faces for his guilty plea on Monday to a single count of dereliction of duty is a demotion to the rank of private, the lowest rank in the service, as recommended by a military judge.
More serious charges of involuntary manslaughter and aggravated assault were dismissed as part of a plea deal that cut short Wuterich's court-martial and was decried by a victim's relative as a disgrace.
The outcome appeared certain to stoke outrage among Iraqis, adding to anger over other abuses by US soldiers or contractors, including the 2004 Abu Ghraib prison scandal, during the more than eight years troops spent in Iraq since the US-led invasion that toppled Saddam Hussein in 2003.
Even before it became clear that Wuterich would be spared jail time, the head of the Iraqi parliament's human rights committee, Saleem al-Jubouri, said terms of the deal were "a violation of Iraqis' dignity" and vowed to convene his panel on Wednesday to discuss the matter.
Wuterich, who could have faced a maximum penalty of three months in jail after pleading guilty, showed no emotion as a military judge pronounced his sentence.
But in a pre-sentencing statement he read in court earlier in the day, Wuterich expressed remorse for the slayings and said he realized that his name would always be associated with "being a cold-blooded baby-killer, an out-of-control monster."
Wuterich was accused of being the ringleader in a series of shootings and grenade attacks on Nov. 19, 2005, that left two dozen civilians dead in Haditha, a city west of Baghdad that was then an insurgent hotspot.
The killings were portrayed by Iraqi witnesses and military prosecutors as a massacre of unarmed civilians -- men, women and children -- carried out by Marines in anger after a member of their unit was killed by a roadside bomb.
As part of his guilty plea, Wuterich accepted responsibility for giving negligent verbal instructions to the Marines under his command when he told them to "shoot first and ask questions later," orders that resulted in the deaths of civilians.
Wuterich, in his pre-sentencing statement, said that when he gave that order, "the intent wasn't that they should shoot civilians. It was that they would not hesitate in the face of the enemy."
He said that he and his fellow Marines behaved honorably under extreme circumstances, and that he "never fired my weapon at any women or children that day."
A final decision on a demotion of rank for Wuterich is up to the commander of the Marine Corps Forces Central Command, Lieutenant General Thomas Waldhauser, who had ruled out any confinement as part of the punishment.
Any discharge process faced by Wuterich, a father of three girls, will be separate from his sentencing.