No known major achievements

The development of this aircraft has been attributed to covert action on the part of Mossad. Mossad was able to acquire the plans for a French Mirage III aircraft, which were used directly in the design process of the Kfir aircraft series.The designers at IAI then began work on the project to improve upon the Mirage III, deciding first to find a replacement engine.

Two powerplants were initially selected for trials%u2014the General Electric J79 turbojet and the Rolls-Royce Spey turbofan. In the end, the J79 was selected, not the least because it was the same engine used on the McDonnell Douglas F-4 Phantom II, which the Israelis began to acquire from the United States in 1969, along with a license to produce the J79 themselves. The J79 was clearly superior to the Atar 09, providing a dry thrust of 49 kN (11,000 lbf) and an afterburning thrust of 83.4 kN (18,750 lbf).

In order to accommodate the new powerplant on the Mirage III's airframe, and to deliver the added cooling required by the J79, the aircraft's rear fuselage was slightly shortened and widened, its air intakes were enlarged, and a large air inlet was installed at the base of the vertical stabilizer, so as to supply the extra cooling needed for the afterburner. The engine itself was encased in a titanium heatshield.

A two-seat Mirage IIIBJ fitted with the GE J79 made its first flight in September 1970, and was soon followed by a re-engined Nesher, which flew in September 1971.

An improved prototype of the aircraft, with the name Ra'am ("Thunder"),Made its first flight in June 1973. It had an extensively revised cockpit, a strengthened landing gear, and a considerable amount of Israeli-built avionics. The internal fuel tanks were slightly rearranged, their total capacity being increased to 713 gallons.

There were unconfirmed reports that a number of the original Mirage IIICs, re-engined with the J79 and given the name Barak ("Lightning"),Took part in the Yom Kippur War of 1973, but some sources point out that there is no real evidence that these aircraft ever existed.

The project that would ultimately give birth to the Kfir can be traced back to Israel's need for adapting the Dassault Mirage IIIC to the specific requirements of the Israeli Air Force (IAF).

The all-weather, delta-winged Mirage IIICJ was the first supersonic aircraft acquired by Israel, and constituted the backbone of the IAF during most of the 1960s, until the arrival of the A-4 Skyhawk and, most importantly, the F-4 Phantom II, by the end of the decade. While the Mirage IIICJ proved to be extremely effective in the air-superiority role, its relatively short range of action imposed some limitations on its usefulness as a ground-attack aircraft.

Thus, in the mid-1960s, at the request of Israel, Dassault Aviation began developing the Mirage 5, a fair-weather, ground-attack version of the Mirage III. Following the suggestions made by the Israelis, advanced avionics located behind the cockpit were removed, allowing the aircraft to increase its fuel-carrying capacity while reducing maintenance costs.

By 1968, Dassault had finished production of the 50 Mirage 5Js paid for by Israel, but an arms embargo imposed upon the country by the French government in 1967 prevented Dassault from ever delivering the aircraft. The Israelis replied by producing an unlicensed copy of the Mirage 5, the Nesher (Eagle), with technical specifications for both the airframe and the engine obtained by Israeli intelligence.