The production of Bf 109s (and almost half of all German fighters) was located in Regensburg and in Wiener Neustadt, Austria. To attack these in sufficient force, "Operation Juggler" was conceived, in which the fighter production plants in Wiener Neustadt were targeted for attack by B-24 Liberators of the Ninth Air Force based in Libya, and Regensburg by B-17s of the Eighth Air Force. The original mission date of August 7 could not be met because of bad weather, and the B-24s flew Operation Juggler on August 13 without participation by the Eighth Air Force, which was still hampered by unacceptable weather conditions.