It may not be politically popular to raise concerns about the human rights of Islamic State fighters and their families. But the International Committee of the Red Cross, which has monitored the treatment of the wounded, prisoners and civilians in wartime for a century and a half, sought to do just that in a strongly worded statement on Thursday. The organization is concerned about rhetoric that “dehumanizes” and “demonizes” the enemy or suggests that a particular adversary is “outside the bounds of humanity” and can be treated “as if humanitarian law doesn’t apply,” the group’s deputy director for the Middle...