Where is the Line Between Combatants and Non-Combatants?

Israel has killed Nizar Riyan, a rather top Hamas figure. No apologies called for. Leaders of Hamas are legitimate, indeed, preferable targets, as they're the ones who bear direct responsibility for the violence. Riyan sent his son Ibrahim to be a suicide murderer, back in October 2001, so great was his hatred of the Jews, and he was considered one of the most extreme of the whole sorry gang of murderers.

The attack also killed his wife, three sons, and others.

After his home was hit, there were a series of secondary explosions, clear evidence that he was storing ordinance there. This underlines the problematic of distinguishing between the innocent and the guilty in this nasty little war: A mother who allows her son to go murder Jews at the certain cost of his life: is she innocent? When she allows weapons to be stored in her home, the place she raises her children, is she still innocent? If the children are teenagers or young adults, and they participate in storing those weapons in their bedrooms, are they innocent? Or are they perhaps proud fighters in the fight for their land, a fight that could long ago have been ended had they been willing to compromise?