internecine

adjective2

1. •
   Characterized by struggle within a group, usually applied to an ethnic or familial relationship.

   • The Mongol people were plagued by internecine conflict until Genghis Khan unified them by focusing their aggression outwards on other peoples.
2. •
   Mutually destructive; most often applied to warfare.

   • Internecine strife in Gaza claimed its most senior victim yesterday when militants assassinated one of the most hated security chiefs there.