American units fighting in the Pacific, did not believe in taking Japanese prisoners.

Defending the Driniumor: Operations in New Guinea, 1944 by Dr. Edward J. Drea
The 112th, like other American units fighting in the Pacific, did not believe in taking Japanese prisoners. Prejudice tinted the American soldier's view of the Japanese and increased the savagery of combat. If the sneak attack on Pearl Harbor brought the cauldron of anti-Japanese feeling to a bubble, U.S. military and civilian propagandists continued to stir the witches' brew in order to foment a hyperpatriotism they believed would be beneficial to the war effort. Japanese atrocities, such as using captured 112th troopers for bayonet practice on New Britain, served to confirm stereotypes of the Japanese as subhuman creatures who had to be killed. This refusal to take Japanese prisoners had important operational ramifications. In the 32d Division's G-3 Journal for 4 July 1944 appeared the entry that "1 unarmed Jap killed, on E bank of Driniumor River." Appended to this entry was the following handwritten note: Another prisoner that could have told us if the 41st (Division) had arrived. What effect our bombing had had, possibly when the attack was expected, where were what units. These troops seem to want to fight this war the hard way, they won't take a prisoner.16
The savagery went far beyond the 112th Cavalry. It infected troops of both nations.