Staff Sgt. Robert Bales' pleaded guilty to multiple counts of murder at a hearing at Joint Base Lewis-McChord south of Seattle.
The judge, Col. Jeffery Nance, later accepted the pleas, ensuring Bales will avoid the death penalty. A jury will decide in August whether Bales gets a sentence of life with or without the possibility of parole.
Bales was charged in the March 2012 attacks on two villages near the remote base in southern Afghanistan where he was posted. Most of the victims were women and children, and some of the bodies were burned.