KIEV, Ukraine — An American-backed deal to settle the crisis in eastern Ukraine fell flat on Friday as pro-Russian militants vowed to stay in occupied government buildings, dashing hopes of a swift end to an insurgency that the authorities in Kiev portray as a Kremlin-orchestrated effort to put Ukraine’s industrial heartland under Russian control. But the agreement, reached in Geneva on Thursday by diplomats from the European Union, Russia, Ukraine and the United States, appeared to arrest, at least temporarily, the momentum of separatist unrest in Ukraine’s Russian-speaking east. Armed pro-Russian militants, who have seized buildings in at least 10 towns and cities since Feb. 6, paused their efforts to purge all central government authority from the populous Donetsk region. It was clear all along that for the pact to have a chance of success, the Kremlin would have to pressure the militants to leave the buildings they had […]