Michael

Of course it was a "War Crime." The vast majority of the Jews killed were from conquered countries. Many were from Poland. Ann Frank's family was famously from Holland.

Defeating a country in war then rounding up a group of its citizens, enslaving and exterminating them is certainly a war crime.

As to the rest of your theory, I learned that the Jews, Homosexual, Roma and others were used by the Nazis as convenient "common enemies" to stir up blood lust and other factors which united the Nazi party and helped beat the drum for war. Could Hitler have got the German people to commit to total war without first attacking the Jews, Gypsies and Homosexuals?