In the summer and fall of 1943, realising the war was lost, Papen attended secret meetings with the agents of the US Office of Strategic Services (OSS) in Istanbul. Papen exaggerated his power in Germany to the OSS, and asked for US support to make him dictator of a post-Hitler Germany. US President Franklin D. Roosevelt rejected the offer when he heard of it and told the OSS to stop talking to Papen. From October 1943, Papen and the German embassy gained access to the "Cicero" documents of secret agent Elyesa Bazna, including information on Operation Overlord and the Tehran Conference, which Papen revealed selectively to Inönu to strain Allied-Turkish relations. In January 1944, Papen, after learning via the "Cicero" documents of a UK plan to have the Royal Air Force use airfields in Turkey to bomb the oil fields of Ploiești in Romania, told the Turkish foreign minister Hüseyin Numan Menemencioğlu that if Turkey allowed the RAF to use Turkish air fields to bomb Ploiești, the Luftwaffe would use its bases in Bulgaria and Greece to bomb and destroy Istanbul and Izmir.