Gunmen in the streets, snipers on the rooftops, shooting all the time: Palestinians fight Palestinians in Jenin. Rare clash between Palestinian Authority security forces and the armed Jenin Brigades in the West Bank city as observed by the Washington Post; The PA hints at a similar model in Gaza. Jenin Brigades fighters race through alleys flooded with sewage to evade the gunfire that echoes all around. "Quickly," one of the fighters urges his comrades as they pass through patrols and barricades of the Palestinian Authority security forces. "Watch out," another cautions at an intersection where an improvised explosive device had...