Yes they were. The US Navy and Air Force really had no military need for the F-5, it was really built for export under the MAP, but when Saigon fell, there were a bunch of F-5E's that were destined for the South Vietnamese AF that had nowhere to go. The Navy replaced their Topgun T-38's and the USAF replaced the Aggressor T-38's at Nellis AFB and at Clark AB, PI. with these F-5E's in the early 1970's. The F-5E was used as a MiG-21 simulator for ACM since the acft had similar performance. Both services soon started adopting WP and other non-Friendly nations paint schemes on the F-5's.