WASHINGTON (Reuters) - The Justice Department said on Thursday it sued to revoke the U.S. citizenship of an accused Nazi concentration camp guard who allegedly took an oath of personal loyalty to Adolf Hitler during World War II. It said it filed the lawsuit in federal court in Cleveland against Jakob Miling, 78, a native of the former Yugoslavia who now lives in Lyndhurst, Ohio. The lawsuit alleged Miling served as a guard at the Gross-Rosen concentration camp in Nazi-occupied Poland and at the Sachsenhausen concentration camp in Germany. At the German camp, Miling and other guards manned machine guns...