the autumn of 1945 and 1947, mapped areas in west and central Europe, North Africa and the Atlantic Islands on a large scale in Operation Casey Jones. Casey Jones flights were made by reconnaissance variant RB-24 Liberators (the former "F-7" variant) and RB-17 Flying Fortresses (formerly called the "F-9"). These flights were only supposed to be flown over the Western Allies occupation zones, but there is a strong suspicion that these aircraft also operated over the Soviet zone. Soviet fighters regularly opened fire on U.S. aircraft operating over their occupation zone. On 22 April 1946, a Douglas C-47 near the Tulln Air Base near Vienna over the Soviet zone of Austria was attacked by Soviet Bell P-39 Airacobra fighters. On 9 August, Yugoslavian fighters opened fire on another USAAF C-47 and forced it to land. Rotation of strategic bombers through Europe Soviet activity in Eastern Europe unsettled the western allies. President Harry S. Truman decided to take a hard line with Russia, lest the situation evolve into a new war. In Germany, Fürstenfeldbruck Air Base near Munich, Giebelstadt near Würzburg, and Rhein-Main near Frankfurt were rebuilt to accommodate Boeing B-29 Superfortress bombers. Strategic Air Command (SAC) wanted its B-29 fleet as close to the Soviet Union as possible because of their limited range and it was decided to rotate a portion of SAC's B-29 fleet through Europe. In November 1946, six B-29 bombers from SAC's 43d Bombardment Group at Davis-Monthan Air Force Base, Arizona were deployed to RAF Burtonwood, England and from there to various bases in Germany as a "training deployment." The B-29s were flown to bases in France, Turkey, Greece and were flown along the borders of Bulgaria and Russia over the Black Sea as part of "show the flag" operations. In May 1947, SAC began additional "training deployments" that stationed a number of B-29s in Germany at Giebelstadt and Fürstenfeldbruck. These B-29 squadrons were constantly rotated back to the United States. being replaced with new squadrons in rotation. SAC also deployed B-29s to the United Kingdom where they were rotated through RAF Marham, RAF Waddington, RAF Scampton and RAF Lakenheath. The United States also provided military aid to the Greek Air Force to help the nation resist the communists. AT-6 Texan trainers and C-47 Skytrain transport aircraft, along with armored vehicles, small arms weapons, munitions and radar were provided. In Turkey, various intelligence gathering aircraft were deployed