Nellis' 4477th Tactical Evaluation Flight ("Red Eagles") operated MiG-17s, MiG-21s and MiG-23s at the Tonopah Test Range Airport (late 1960s-) to simulate combat against U.S. combat aircraft. Named Constant Peg in 1980, the operation assessed the Soviet technology and developed adversary tactics for dissimilar air combat training. After completion of training, the Aggressor pilots were assigned to the DACT squadrons, one of which was assigned to Nellis. During the 1970s, a site northwest of Nellis evaluated a Soviet "Barlock" search radar to develop techniques for countering Soviet air defense systems.