When Two Cultures Collided

Recently I watched "BattleShip" a movie about a group of aliens came from far distance to conquer earth. Then I realize that an astronomer has said " This is like the Columbus meet the Indians, except we were the Indians".



Could it possible when someone out there has receive our signal and verified that the existing of E.T that is us the earth people could make some contact without the army interference ? We learn from history that when two cultures collided, war will happen. Conquerer wants some minerals and the defender wants to live normally.