Nellis Air Force Base ("Nellis" colloq.) is a United States Air Force installation in southern Nevada with military schools and more squadrons than any other USAF base. Nellis hosts air combat exercises such as Exercise Red Flag and close air support exercises such as Green Flag-West flown in "Military Operations Area (MOA) airspace". associated with the nearby Nevada Test and Training Range (NTTR). The base also has the Combined Air and Space Operations Center-Nellis.