Key Point: Israel and China have reasons to deny it.
The J-10 “Vigorous Dragon” is a mainstay of China’s effort to modernize its large fleet of single-engine jet fighters, with 350 already in service. An agile tactical fighter similar to the ubiquitous F-16 Fighting Falcon, the Vigorous Dragon was the first domestic Chinese design roughly on par with Western and Russian fourth-generation fighters.
However, there is considerable evidence that the J-10’s development was heavily informed by a jet fighter developed by Israel with U.S. engines in the 1980s.
Israel first manufactured its own jets after its order of French Dassault Mirage Vs was embargoed in 1967. Israeli agents obtained Mirage V schematics (and most likely manufacturing components and even airframes), allowing Israel Aerospace Industries to produce two domestic clones: the Nesher and the improved Kfir. These both served with the IAF and were exported broad.
Between 1969–1979, the IAF received high-performance twin-engine F-4 Phantom fighters and F-15 Eagles from the United States. However, it still wanted a cheaper single-engine tactical fighter to replace its increasingly vulnerable A-4 Skyhawk and Nesher jets. So why not also build the Nesher’s replacement domestically?
The resulting dapper IAI Lavi (Lion Cub) had delta-wings (good for high-speed performance) combined with canards, a second set of small wings near the nose for improved lift and maneuverability. The Lion Cub was so maneuverable it was aerodynamically unstable, but an advanced quadruple-redundant fly-by-wire flight control system counter-acted the instability.