The American campaign in Afghanistan suffered a double blow Thursday: The Taliban broke off talks with the U.S., and President Hamid Karzai demanded NATO troops immediately pull out of rural areas in the wake of the killing of 16 civilians. The moves represent new challenges to America's strategy for ending the 10-year-old war at a time when support for the conflict is plummeting. Part of the U.S. exit strategy is to transfer authority gradually to Afghan forces. Another tack is to pull the Taliban into political discussions with the Afghan government, though it's unclear that there has been any progress since January. Although Karzai has previously said that he wanted international troops to transition out of rural areas, the apparent call for an immediate exit is new. Karzai also said he now wants Afghan forces take the lead for countrywide security in 2013, in what appeared to be a move to push the U.S. toward an earlier drawdown. A statement released by Karzai's off...