The Atlas Cheetah programme grew out of South Africa's requirement for a modern fighter and strike aircraft in the 1980s. There was a need for more advanced aircraft to attain an edge over the ever more sophisticated Soviet aircraft such as the MiG-23 being supplied to Angolan and Cuban forces in action against South African forces in the Border War. Furthermore, the increasing cost of maintenance due to sanctions and the age of the aircraft used by the SAAF had to be addressed. The arms embargo imposed at the time by United Nations Security Council Resolution 418 prevented South Africa from purchasing new aircraft from other countries, thus making an upgrade of existing aircraft the only option. By this stage, the South African aviation industry had reached the level of technical capability to make a large and sophisticated upgrade possible, leading the SAAF to make the only possible decision: to extensively upgrade one of the existing types in service while an advanced indigenous fighter, the Carver, was under development.
At the time the SAAF's fast jet fleet consisted of Dassault Mirage III (EZ/CZ/BZ/DZ/D2Z/RZ/R2Z) and Mirage F1 (AZ/CZ) aircraft. Though the Mirage F1s were the most modern of the fleet, having been delivered from 1977 onwards, they were the primary element of South Africa's air defence and strike fleet and to withdraw them for an upgrade would have left an unacceptable gap in its air defence and strike capability. In addition there were already a few successful Mirage III upgrades from which to learn, such as the Israeli Kfir and Mirage III NG, so the SAAF's Mirage III fleet was chosen as the basis for the upgrade, to be known initially as Project Cushion.
The work was carried out by Atlas Aviation (formerly Atlas Aircraft Corporation and lately Denel Aviation), using expertise partly gained by recruiting technicians from Israel's aborted IAI Lavi fighter project. The upgrade consisted of a complete refurbishment of the airframe down to zero hours (in which some 50% of the original airframe was said by Atlas to have been replaced), the fitting of non-moving canards (Cheetah D & E having slightly smaller (70%) canards than that of the Cheetah C and Kfir) just aft of the engine intakes, two new stores pylons at the wing roots, an aerial refuelling probe, new ejection seats, a more powerful engine (the SNECMA Atar 9K50C-11 [upgraded in South Africa]) in the D and C variants, a new main wing spar along with a new "drooping" leading edge and a dog-tooth incision on each wing, modern elevons controlled by a twin computer flight control system, and strakes on the nose to improve the Cheetah's high-Angle of attack (AoA) performance. The aerodynamic refinements alone increased the turn rate by 15%, increased the AoA, reduced the minimum airspeed to 100 kt and increased maximum take-off weight by 700 kg. However, it also resulted in a 5% decrease in maximum level speed and acceleration.
In addition, a highly sophisticated avionics, radar, EW and self-protection suite was installed, necessitating a lengthening of the nose. This entailed the fitting of an EW suite which included missile and radar warning sensors. Other features included the aircraft's self-protection system, which consisted of electronic jammers and chaff/flare dispensers that engaged automatically; the integration of a South African helmet-mounted sight and an oversized head-up display (HUD); the installation of an advanced Pulse-Doppler radar and sophisticated cockpit instrumentation.
Most leading aviation publications suspect that Israel Aircraft Industries was involved in at least the initial stages of the upgrade, and that some of the upgrade's components were sourced from Israel. At least five IAI Nesher fighters may have been acquired from the Israeli Air Force for Cheetah trials and later absorbed into the existing fleet.