It is important to say that during the war all countries conducted propaganda among their soldiers, that the enemy is not a man.
For example, among the American soldiers, so-called “hunting licenses” were distributed.
One of them sounded like this: “The season of hunting for the Japanese is open! There are no restrictions! Hunters are rewarded! Free ammunition and equipment! Join the US Marine Corps!”. In fact, there was a legalization of human hunting for humans. Therefore, there is nothing surprising in that American soldiers during the battle for Guadalcanal, killing the Japanese, cut off their ears and kept them as souvenirs.
Necklaces were made from the teeth of the dead, skulls were sent home as souvenirs, and ears were often worn around the neck or on a belt. In 1942, the problem became so massive that the command was forced to issue a decree that forbade the appropriation of enemy body parts in the form of trophies. But the measures were belated, because the soldiers had already fully mastered the technology of cleaning and cutting skulls.
The soldiers were very fond of taking pictures with them. This “fun” is firmly entrenched. Even Roosevelt was forced to abandon the written knife, which was made from the bone of the Japanese’s leg. It seemed like the whole country was going crazy.
Light at the end of the tunnel appeared after the furious reaction of the readers of the newspaper “Life”, in which published photos (and there were a myriad of them) caused anger and disgust.