Russia and the United States agreed early Saturday on a new plan to reduce violence in the Syrian conflict that, if successful, could lead for the first time to joint military targeting by the two powers against Islamic jihadists in Syria . The agreement was reached after 10 months of failed attempts to halt the fighting and of suspended efforts to reach a political settlement to an increasingly complex conflict that began more than five years ago. The conflict has left nearly half a million people dead, created the largest refugee crisis since World War II and turned Syria into a prime incubator of recruiting for the Islamic State and the Nusra Front, an affiliate of Al Qaeda. Secretary of State John Kerry and his Russian counterpart, Sergey V. Lavrov, announced the agreement in Geneva after weeks of negotiations that were marred, in President Obama ’s words, […]