Selling American weapons to China

Since the Tiannaman Square massacre, the United States has blacklisted China from getting access to certain advanced weapons technology. Countries which the US does provide weapons to are subject to reexport rules designed to prevent China from getting access to them.

Israel doesn't need to pay for advanced military warfare systems from the US and they are exempt from paying the license to reproduce some of these systems within their own military industry. With these privileges they sells advanced (fire control radar technology, laser targeting technology, aero foil design secrets, missile technology, UAV technology, and tactical satellite) technology via allied country defense companies. 

Example of technology recycled to China

IAI Lavi - The IAI Lavi is a rip off of Lockheed's f16. Its advanced avionics and fire control radar as well as the engine that made up the aircraft were all borrowed products of American industries. This technology was reexported to become China's J10. the aircrafts fire control radar has been reported by official sources to be a knock off of the Israeli made elm 2021 radar, produced by Elbit Systems, who received the technology from the united states.

Python 3 - Israel's python 3 air to air missile is an upgraded version of the us built aim 9l side winder heat seeking missile. Israel provides China with the python 3.

An Israeli official has admitted it 

David Larry, the general director of Israel's ministry of defense admitted in an interview that Israel had sold "some technology on aircraft," and that some Israeli contractors may not have "clean hands".

The U.S. Knows

In 1995 the us government raised concerns over Israel's reexporting of Lavi technologies to China. Despite Israeli denials, in 1997 us naval intelligence stated a strong conviction that Israel was selling us derived technologies rom the Lavi program to China in Assistance of its J10 program. Speaking to the New York times in 1993, CIA Chief, R James Woolsey admitted that the CIA was completely aware that Israel had been providing China's military with advanced weapons systems for jets tanks and missiles. 

The Israel Lobby helps cover it up

The Israeli lobby power has prevented civilian and military intelligence agencies from mentioning it in investigative reports.