In this Aug. 14, 2012 photo, a U.S. Air Force KC-135 Stratotanker sits on the tarmac at Kadena Air Base on Japan&#x27;s southwestern island of Okinawa. For decades, the U.S. Air Force has grown accustomed to such superlatives as unrivaled and unbeatable. Now some of its key aircraft are being described with terms like decrepit.   (AP Photo/Greg Baker)
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