So simple put there have been times in the past and maybe in the future where you were/will be obligated to kill women and children.
Chabad.org is not a good source for this information?
Rabbis Freeman and Moss, both of whom are extremely learned and talented, are, with all due respect, not considered Halachic authorities (neither am I). That is why I pointed you to an actual Halachic authority (which I don't think anyone here would claim is non-traditional, or non-mainstream).
The way I understand Maimonides (especially taking into account the section of his compendium where he placed this Halacha) it is a Mitzvah that pertains to a king, and not upon each individual jew.
Once the King wages war, soldiers acting on his behalf cannot be considered murderers (as I am sure you wouldn't consider any of the participants in the bombings I referenced above).