I am unsure as to why this is, but it has been a problem for a long time. There are very few Jews in Japan, but they are targeted in a variety of publications. I wasn't even really aware of this until I went to the WWII museum in New Orleans and saw the anti-Semitism campaign launched by the Japanese empire during the Second World War. I went home and started looking up various information. It was a bit shocking.
If the US Army is going to distribute reading material, then it is responsible for its content.