> those Jews are by definition heretics (even if tinok sh’nishbu).
you need to read up on yor chofetz chaim and rambam. Join daf yomi as this discussion is coming up in Shevuos 5 … tinok sh’nishbu is NOT heretic and is NOT to be obligated to be hated. You should like Yoav run to your cheder teacher and slain him in case he taught you wrong.
In case of the soldiers mentioned here – recruited into Russian army – were often the poor and orphans – often using questionable methods protecting “more observant” Jews (guilty of violating mitzvos related to orphans and poor), and thus having less chances of being observant. More “regular” Jews were recruited into the democratic Polish army, but still even if they were “regular” Jews (that is observant when in the community), their observance decreased when in the goyishe army… Steipler, for example, was conscripted into the Russian army and was mesiros nefesh for keeping mitzvos but not everyone was.
There is a sheila of such soldiers addressed to Chofetz Chaim (yes, they asked shailos) about eating non-kosher meat. His response was – you are allowed to eat the meat but not such the bones (i.e. not to enjoy it).
Another story I heard is from R Berel Wein – during his father’s class a goyishe/uneducated dressed person came into beis midrash. Rav’s father interrupted the class and got up to shake the man’s hand. He later eplained to the surprised Berel that this was a kantonist who went thru 25 years of Russian army, is very much an ignoramus and not a baal middos, but he came back to the Jewish community and deserves a lot of respect.