During World War II, some members of the United States military mutilated dead Japanese service personnel in the Pacific theater of operations. The mutilation of Japanese service personnel included the taking of body parts as "war souvenirs" and "war trophies". Teeth and skulls were the most commonly taken "trophies", although other body parts were also collected.
The phenomenon of "trophy-taking" was widespread enough that discussion of it featured prominently in magazines and newspapers, and Franklin Roosevelt himself was reportedly given, by a U.S. Congressman, a gift of a letter-opener made of a man's arm (Roosevelt later ordered that the gift be returned and called for its proper burial). The behavior was officially prohibited by the U.S. military, which issued additional guidance as early as 1942 condemning it specifically. Nonetheless, the behavior continued throughout the war in the Pacific Theater, and has resulted in continued discoveries of "trophy skulls" of Japanese combatants in American possession, as well as American and Japanese efforts to repatriate the remains of the Japanese dead.
A number of firsthand accounts, including those of American servicemen, attest to the taking of "trophies" from the corpses of Imperial Japanese troops in the Pacific Theater during World War II. Historians have attributed the phenomenon to a campaign of dehumanization of the Japanese in the U.S. media, to various racist tropes latent in American society, to the depravity of warfare under desperate circumstances, to the inhuman cruelty of Imperial Japanese forces, lust for revenge, or any combination of those factors. The taking of so-called "trophies" was widespread enough that, by September 1942, the Commander in Chief of the Pacific Fleet ordered that "No part of the enemy's body may be used as a souvenir", and any American servicemen violating that principle would face "stern disciplinary action".
Trophy skulls are the most notorious of the souvenirs. Teeth, ears and other such body parts were occasionally modified, for example by writing on them or fashioning them into utilities or other artifacts.