Who's your enemy? Why fight? Over the course of three years, Belgian-Tunisian photojournalist Karim Ben Khelifa has traveled to both sides of the world's longest-simmering conflicts to ask these pointed questions. What he heard from combatants in the Gaza Strip, the disputed Kashmir region along the India-Pakistan border, and tribally divided South Sudan captures the futility of wars that never end -- and can't be won. Tragically, bitter rivals are often fighting for the very same reasons.