Unfortunately (and to my great puzzlement), Israel has illegally transferred much of our technology to the Chinese as well.
Oft-repeated, but a false rumor started by the Russians who claimed a prototype Lavi was moved to China.
I am a former IAF officer, and I was involved in the Lavi project.
First an appeal to common sense: look at the J-9, which predates Lavi. The evoltution is clear.
Second, the whole prototype-in-China business is easily refuted. When the Lavi was cancelled on 1987, a total of five airframes had been built. Prototypes #1 and #2 were completed prototypes, while #3, #4, and #5 were incomplete (#4 and #5 being little more than the basic frame).
Parts from unit #1 and #2 were pulled to complete unit #3 as the private-venture technology demonstrator (TD) aircraft.
#3 remains in the IAI hanger, and I’ve seen it myself.
The gutted unit #2 was put in the Israeli Air Force museum at the Hatzerim Airbase for static display, and the rest (gutted #1 and #4, & #5) were parted out.
That said, there WAS a technology transfer, but NOT of American technology.
Certain people ILLEGALLY sold elements of the Israeli-made ELM-2021 radar system, which can simultaneously track six air targets and lock on to the four most threatening targets for destruction.
They were fired/prosecuted, as appropriate.
This illegally-sold radar system probably has made its way into a number of Chinese and other enemy countries.