Russia has not formally signed a contract to sell the Sukhoi Su-35S Flanker-E and S-400 surface-to-air missile system to China. Right now, Moscow has only agreed in principle to sell those advanced weapons to China.

“First of all, let’s be accurate. We have not sold yet,” said retired Lt. Gen. Evgeny Buzhinsky (Ret.), chairman of the executive board of Russia’s PIR Center, during a lunch event at the Center for the National Interest on Nov. 15. “We are in the process of very tough and very difficult negotiations on these issues.”

The Russians and the Chinese have made the decision on the sale in principle, but the deals are not finalized. However, in the meantime, the Kremlin and the Chinese leadership have signed an agreement to protect Russian intellectual property—which Moscow hopes will prevent Beijing from stealing its technology. “The principle decisions on S-400 is taken—the principle decision on Su-35 is taken,” Buzhinsky said. “We signed the protection of intellectual property agreement, which was a precondition for the supply of Su-35.”

But Russia is well aware that an agreement with China to protect its intellectual property might well be meaningless. Buzhinsky said that Russia is not about to hand over the crown jewels of its technology to China without taking precautions. The Chinese version of the Su-35 will not be the same as the one used by the Russian Air Force. “We have export version and a version for our own use,” Buzhinsky said. “The Chinese are very good at copying all kinds of stuff.”

Nonetheless, Russia is confident that its technology will be safe in Chinese hands—particularly the all-important Saturn AL-41F1S engine. “They cannot produce engines,” Buzhinsky said. “We agreed to supply engines for the Su-35, but fortunately—my technical colleagues told me—that it is practically impossible to copy that engine because it is practically impossible just to reach the heart of the engine without breaking it completely.”

China is expected to purchase 24 advanced Su-35s from Russia—but most observers believe that Beijing’s motive is to harvest those aircraft for their technology. While Beijing is working on developing advanced stealth fighter aircraft such as the J-20 and J-31, the Chinese have proven to be woefully behind in developing jet propulsion technology. Indeed, the J-20 is known to use Russian Salut AL-31FN engines—which were originally designed to power variants of the Russian Su-27 Flanker.

While Moscow is confident that China will not be able to pick the Su-35 and S-400 clean of their advanced technology, Beijing has proven to be remarkably adept at technology theft. It remains to be seen if the Kremlin’s safeguards will be effective in preventing the Chinese from reverse engineering the S-400, Su-35 and its engines. Only time will tell.  

Dave Majumdar is the defense editor for the National Interest. You can follow him on Twitter: @davemajumdar.