Modification of normal language into euphemism is one kind of pyschological warfare. Keen gives examples of how we demonize the enemy. War propaganda tends to claim that only the enemy kills civilians, tortures POWs, and practices aggression and imperialism. Faces of the Enemy is ultimately a disappointing and disturbing book. Keen's preaching fails to recognize that conflict is a perpetual reality in this world.
Conflict precedes propaganda and the technology of warfare.
Not all enemies are figments of our imagination. True pacifists are extremely rare in this world. The reason for this is that aggression, a competitive nature, and group solidarity are traits that confer distinct advantages for survival to animals and Homo sapiens alike. The existence in the modern world of nuclear, biological and chemical weapons does not change the dynamics of conflict and competion. Certainly there are often ways in which conflict between individuals, groups or nations can be resolved peacefully.