Since 1975, the U.S. Air Force has been holding large scale training exercises called Red Flag at Nellis Air Force Base in Nevada. These exercises pit a Blue Force against an opposing Red Force which has "Aggressor" units equipped with F-16C Block 32 and 42 to simulate MiG and Sukhoi fighters. Similary, the U.S. Navy's "Adversary" units used the purpose-built F-16N, which were based on the F-16C Block 30 in their own famous TOPGUN school at Miramar in California. These "Aggressor/Adversary" aircraft often had colorful camouflage schemes.