Robert "Doc" Davenport, a Marine medic trained to both save people and kill them, was among those struggling to digest the appalling news.
"It makes it harder to do my job," he said, explaining he'll now think twice about dressing the wounds of injured Iraqis.
"If we run across one of them and he needs my help, it will be harder for me to do it," he added.
Many Marines on this desert base - affectionately known as "Snakepit" - said they believe they were sent to Iraq not to hurt people, but to free them from Saddam Hussein's ruthless grip.
"We want to help these people and look what they're doing to us," said more than one shocked Marine.
"What we should do is go in there and kill every last soul," growled Sgt. Mike Brady.