Authorities in Norway have arrested a Norwegian man who worked as a security guard at the U.S. embassy in Oslo, accusing him of passing sensitive information to Russia and Iran. Under interrogation, the man, identified as Mohamed Orahhou, 27, admitted to collecting and sharing information with an officer from Russia’s domestic intelligence service, the S.V.R., as well as with unspecified Iranian officials, according to Norwegian authorities and Mr. Orahhou’s lawyer. The authorities have...