It sounds like science fic­tion, but it is fact: On the battlefields of Iraq and Afghan­istan, robots are killing America’s ene­mies and sav­ing Ameri­can lives. But today’s Pack­Bots, Preda­tors, and Ravens are rela­tively prim­itive machines. Peter Singer says the coming generation of “war-bots” will be im­mensely more sophisti­cated, but their devel­op­ment raises troubling new questions about how and when we wage ­war.