China’s air force announced it is about to unveil its newest stealth jet fighter, the J-35, which U.S. officials say was built with the help of stolen American military technology.

The J-35 will be declassified and shown for the first time at the annual Zhuhai air show scheduled to begin Nov. 12, Chinese military officials announced Tuesday. The aircraft has been in development for more than 10 years.

“For the first time, new equipment such as the medium-weight, stealth multi-role fighter J-35A, the HQ-19 surface-to-air missile and a new type of reconnaissance and strike unmanned aerial vehicle will be on display,” Col. Niu Wenbo, a military spokesman, told CCTV state television. A photo of the J-35 was released but no other details were provided.

It is the second radar-evading stealth jet in the Chinese military arsenal, after the J-20.

Both jets are viewed as an effort by China to match the U.S. military’s F-35 and F-22. The J-35 will also be used on China’s growing fleet of aircraft carriers. Two are deployed, and a third is being built.

The Pentagon’s most recent annual report on the Chinese military said the J-35 and J-20 are the most advanced warplanes among the 1,300 fourth- and fifth-generation fighters China has fielded. 

A defense official said the J-35 is an export-oriented, low-end stealth aircraft that includes technology used in the J-20.

Photo comparisons of the J-35 reveal that the main design features are similar to those of the multi-service U.S. F-35 stealth jet.

Documents disclosed by former National Security Agency contractor Edward Snowden a decade ago revealed that the J-20 was built with stolen American technology used in the F-35.

The documents revealed that Chinese military hackers stole more than 50 terabytes of data from U.S. government and defense contractor networks, data that included details of the F-35 stealth radar and engine secrets, as well as details of the F-35’s AN/AAS-37 electro-optical distributed aperture system.

Engine schematics included details on the methods used by the turbine to cool gases, along with leading- and trailing-edge engine treatments and engine heat reduction data, all key elements of stealth design.

The technology was incorporated into the J-20.

Other stolen F-35 features now in both the J-20 and J-35 are said to include an electro-optical targeting system, a “diverterless supersonic inlet,” a thrust-vectoring jet nozzle and a fire-control array radar system.

A Chinese military unit called a Technical Reconnaissance Bureau in Chengdu province conducted the hacking, with the data then passed on to the state-run Aviation Industry Corp. of China, which makes both the J-20 and the J-35. China has deployed an estimated 195 J-20s.

Retired Navy Capt. Carl Schuster, former director of operations at the Pacific Command Joint Intelligence Center, said the new J-35A will likely be used for the Chinese navy.

“The J-35 made its maiden flight in 2021, but as a derivative of an earlier prototype, it may be ready for production by early next year,” he said.

The J-35A is likely outfitted with improved design features and more powerful engines, he said.

Capt. Schuster said both the J-20 and J-35 benefited from China’s massive open source and cyberespionage effort over the past 25 years. “That has enabled Beijing’s aviation industry to advance far beyond the days of reverse-engineering foreign aircraft and systems,” he said.

A Chinese Defense Ministry website said the J-35 was built by the Shenyang Aircraft Design and Research Institute, part of the Aviation Industry Corp.

“The J-35 series is designed to be one platform with multiple variants for both Chinese air and naval forces,” the website said.

Wang Mingzhi, a military analyst, said on the website that the J-20 is a “heavy-duty stealth fighter jet” and the J-35 is a “medium-sized multi-role stealth fighter jet.”

“The primary distinction is that the J-20 focuses on air superiority missions, while the J-35A is versatile, capable of pursuing air superiority and accomplishing a variety of ground and maritime strike missions,” Mr. Wang said. “In future operations, these two aircraft can precisely target at both land and sea objectives in a coordinated manner, thus playing a crucial role for achieving air superiority.”