WASHINGTON - Iraqi leaders will be hard pressed to craft a lasting political settlement or improve their security capabilities in the next year and a half, the U.S. intelligence community concluded in a report that raises new uncertainty about the prospect for withdrawing American troops. Months in the making, the collaborative assessment by 16 spy agencies says that growing and entrenched polarization between Shia and Sunni Muslims, inadequate Iraqi security forces, weak leaders, and the success of extremists' efforts to use violence to exacerbate the sectarian war all create a situation that will be difficult to improve. "We think it...