In August 1964 the USAF took its first delivery of F-5As and immediately decided to send a few machines to the combat zone in order to test their capabilities. The so-called 'Skoshi Tiger' program was organized in October 1965, coinciding with the arrival of 12 F-5As, partially modified for war purposes and furnished with 'proboscis' equipment for refueling in flight. The fighter-bombers operated at first with the 4503rd TFW, and in the course of 2,500 hours of tactical support and reconnaissance missions gained experience that proved extremely valuable for launching the next, more powerful F-5E version, which took the name Tiger II in recognition of the aircraft's contribution to the Skoshi Tiger operation. The 12 F-5As of the 4503rd TFW, together with six new machines, were handed over to the 10th Fighter Command Squadron, attached to the 3rd TFW at Bien Hoa, and in 1967 the USAF delivered them to the VNAF. The F-5s were the first and only jet aircraft belonging to the newly formed South Vietnamese Air Force, which later received a number of F-5Es, used in action until the final collapse. Many of these F-5Es were captured by the North Vietnamese in perfect working order.