An American soldier who murdered 16 people including children in southern Kandahar province of Afghanistan has said he lost compassion for Afghans and Iraqis and that he had been “consumed by war” by the time of the massacre.

In an eight-page letter addressed to senior Army officer at Joint Base Lewis-McChord in Washington state, the former Staff Sgt. Robert Bales, asked for his life sentence to be reduced.

Bales also added in the letter obtained via the Freedom of Information Act by the News Tribune that “I planted war and hate for the better part of 10 years and harvested violence.”

“After being in prison two years, I understand that what I thought was normal was the farthest thing from being normal,” Bales wrote in the letter.

He also wrote over his combat tours he came to hate “everyone who isn’t American” and became suspicious of local residents who might be supportive of those fighting Americans.

At least 22 people including women and children were shot during pre-dawn raids on two villages in Kandahar Province in March 2012.

The brutal killings prompted such angry protests that the U.S. temporarily halted combat operations.