With fighting intensifying in eastern Ukraine and the White House weighing whether to send arms to bolster the government’s forces, Western leaders embarked on a concerted diplomatic effort on Thursday aimed at ending a conflict that has strained relations with Russia. Despite the burst of activity, the prospects of achieving a new peace plan have been clouded by deep suspicion of Moscow’s aims in Ukraine. At the same time, the arrest in Kiev on Wednesday of a senior officer on charges of spying for Russia has raised concerns that the Ukrainian military has been infiltrated, complicating any plans for sending arms to Kiev. While the United States has provided weapons to allies in similarly unstable circumstances, including in Afghanistan and Iraq, Russia’s long historical ties to the Ukrainian military and security apparatus present an unusual challenge. “Very often one cannot tell where the F.S.B. stops and […]