It was ruled as such by the ICTY in Prosecutor v. Krstic.
The French NA troops were the ones I referred to, not clearly enough. They were quite heroic and Americans have probably never been able to fathom that 'natives' would willingly fight for their 'colonial oppressors'.
And I was referring to France's West African troops and, less directly, other African troops. You're right, of course, that many Americans have never understood why colonial subjects would fight on the side of their imperial overlords. It's a testament to their understanding of the Nazi menace that they were willing to put their local struggles for freedom on hold in order to help save the entire world.
Soviet citizens are another matter I'd omitted. I had a friend in the Seventies who had been part of the White Army, the Ukrainian Resistance Army, and generally hated Stalin...until someone invaded the homeland and he was instantly part of the Red Army fighting Germans. (He also became part of the Waffen SS fighting Stalin, a German prisoner (twice), an escapee, a Legionnaire fighting Uncle Ho/General Giap, and, when I met him, a Master Sergeant again fighting the latter gentlemen.)
Your friend sounds like a walking military history of the mid-20th century.
No matter what you may believe about the typical muslim, Hitler's message was widely and well received in muslim states and communities, probably even many in the Soviet Union and surely in Egypt, Albania, etc.
I don't doubt Hitler's message was widely received in the Muslim world. It was widely received the world over, after all. However, it's important to note that the number of Muslims who took up arms for the Nazis was far smaller than the number of Muslims who took up arms against the Nazis.
Add to that the territorial hatreds and prior German influence in Croatia and elsewhere, and there WAS a direct Nazi/Islamist linkage forged as soon as the two came together. Judging from the Islamist regimes and Islamist movements across the middle east today, and the 'Palestine' vs 'the Jews' cant associated with the entire area - I'd have to guess that the attraction has not faded too very much.
I can't speak to whether the attraction has continued from the past or is something new that claims WW2-era antecedents. We need recognize is that it is real and growing in the present age. Insulting the WW2 service of Muslim troops does nothing for our cause. In fact, I would go so far as to say that the people who say such things are sowing and nourishing the "Clash of Civilizations" that Osama calls for. There's something very very low about insulting an 85+ year old war veteran who put his life on the line to defeat Hitler. That kind of man is many things, but "phoney" is not one of them.
Kind of what I meant by seeing no proof...
The ICTY has zero validity as a legal body, it's not even doing too well as a 'Victor's Forum For Vendication Of Otherwise Indefensible Acts'.