The Secret Behind Israel’s Kfir Fighter: Espionage, Innovation, and Survival

The year was 1968, and Israel was facing an urgent crisis. The victory in the Six-Day War had come at a cost, as you remember from the previous newsletter, France, once a key arms supplier, had turned its back on Israel. President Charles de Gaulle, condemning Israel’s preemptive strike, imposed a strict arms embargo, cutting off access to the powerful Dassault Mirage 5 fighters that Israel had already paid for.

Israel needed a solution.

Somewhere in Switzerland, in the quiet offices of Sulzer, a company licensed to produce components for the Mirage III’s SNECMA Atar 9C engine, an unassuming Swiss engineer named Alfred Frauenknecht went about his work. He was not a spy, nor a man with strong political beliefs—just an engineer in need of money. And money, as it turned out, was something Israel was willing to provide. An operation was put in motion to acquire the Mirage blueprints by any means necessary.

Israeli intelligence, known for its daring operations, identified Frauenknecht’s financial troubles and made an offer: a large sum of money in exchange for technical documents. Frauenknecht hesitated, but the lure of wealth proved too strong. Slowly, methodically, he began to collect thousands of classified blueprints—detailed schematics of the Mirage’s airframe, avionics, and most importantly, the Atar 9C engine.

For the next few years (1968-1969), Frauenknecht smuggled out documents in secret, passing them into the hands of Israeli intelligence. The blueprints, once in Israeli possession, were studied by engineers at Israel Aerospace Industries (IAI). With these stolen plans, Israel reverse-engineered the Mirage 5, producing an almost identical aircraft—the IAI Nesher.

But Israel didn’t stop there. Armed with this knowledge, their engineers went further, replacing the Atar 9C engine with the more powerful General Electric J79, the same engine used in the American F-4 Phantom II. This modification required significant engineering changes, including structural reinforcements to handle the increased thrust and upgraded avionics to integrate both Israeli and American weaponry

And then came one of the biggest aerodynamic improvements, the addition of canards, small forward wings placed near the cockpit. These were introduced in the Kfir C2 and later models, drastically improving:

• Maneuverability – The aircraft could turn tighter, making it deadlier in dogfights.
• Takeoff and landing performance – Shorter takeoff distances and better control at low speeds.
• Stability – Compensating for the heavier engine and increasing overall control.

The result? A new aircraft—the IAI Kfir—a fighter even deadlier than the Mirage it was based on.

Meanwhile, Frauenknecht’s activities did not go unnoticed. By 1971, Swiss authorities uncovered the breach. Frauenknecht was arrested, charged with espionage, and sentenced to four and a half years in prison. The case caused an international scandal, but by then, the damage was done. Israel had what it needed.

By 1975, the first IAI Kfirs rolled off the production line and entered service with the Israeli Air Force. Later, the fighter was exported to Colombia, Ecuador, Sri Lanka, and even the United States (as the F-21, for training).

The Mirage had been born in France. But its Israeli descendant, the Kfir, was something entirely different—the product of necessity, espionage, and engineering ingenuity, proving once again that Israel could not be outmatched, even by an arms embargo.