Investigators say ISIS is reaching into American homes to find their newest recruits and their next victims. Of all the weapons used by terrorists one of the most dangerous is social media.

 When Islamic State militants posted a video over the weekend showing the grisly killing of a Japanese journalist, Prime Minister Shinzo Abe reacted with outrage, promising “to make the terrorists pay the price.”Such vows of retribution may be common in the West when leaders face extremist violence, but they have been unheard of in confrontation-averse Japan — until now..