Numerous reports have appeared in the media of late regarding a deal whereby Russia would export 24 Sukhoi Su-35 Flanker fighters and four Ladas-class submarines to China. The Russian government has officially denied these reports. Numerous unofficial sources, however, indicate that S-400 antiaircraft missiles and IL-476 transport planes could be included as part of a large deal. That would be the largest China-Russia sale package since 2002.

Su-35 export rumors have been around for more than four years, but the most recent reports seem to have the most credence. China’s defense ministry has not explicitly denied the reports. At the same time, numerous unofficial Chinese sources are indicating the deal is possible. Amid the speculation, it’s worth looking at what China and Russia would like to get from this deal.

First rumors of a deal for 48 Su-35 emerged in 2008. Su-35 was not ready for production at that time, but China’s own efforts in producing Jian-11 Bs were also having some setbacks.

It appeared possible that China would purchase two squadrons of Su-35 as an interim option before the next generation fighter jets come into service. When the rumors remerged in 2010 and 2012, it made less sense, because J-11B, the domestic version of the Flanker produced by Shenyang Aircraft Corporation, seemed to have satisfied the People’s Liberation Army. Western and Russian news sources were shocked to see Russia still willing to sell such an advanced aircraft to China even after China “cloned” Russian fighters, but those articles do not seem to have a grasp on reality.

China has two so-called stealth fighter jet programs under development that will probably achieve initial operating capability toward the end of this decade, so it doesn’t make sense for China to buy and then copy a less-capable fighter like the Su-35.

While Shenyang is still developing and producing other variants of Flankers like J-15, J-16, they are for naval aircraft and fighter-bomber roles. Purchasing Su-35s really would not aid Shenyang in those projects.

Finally, China is not exporting any of its Flankers to other countries, so this export deal will not threaten Russia’s other export markets.

If China does purchase Su-35s, it will create a logistical problem in the future. The PLA will need to maintain a new type of aircraft, a new engine, a new generation of Russian avionics, and Russian missiles.

That would seem to be a lot of trouble for just 24 aircraft. So, why is China buying Su-35s?

The most obvious reason is to get their hands on the 117S, the most advanced model of AL-31F engine.

Russia made it clear to China early on that it would only be willing to sell 117S to China as part of a Su-35 order. Twenty-four is probably the minimum number of Su-35s that Russia would be willing to sell to China to allow Chinese access to 117S engine.

China does have the largest maintenance, repair, and overhaul plant for the AL-31F engine outside of Russia. All maintenance work for AL-31 is done inside China. One assumes 117S maintenance and life extension work would also be done there.

While China is making good progress in improving the reliability of WS-10A, turbofan engines remain the Achilles’ heel of its military-industrial complex. If there is one problem that can cause real delay in China’s J-20 stealth fighter, it would be the lack of a reliable engine solution in its development and early deployment.

The 117S would also be possible options for J-10 and J-15/16 projects.

Should Russia be nervous about exporting the Su-35 and 117S to China?

Maybe, but there is really no reason for China to try to copy the Su-35 now. While they could try to copy 117S, the more likely scenario is for China to place large orders of it for the J-10 program.

The deal for four Lada submarines is more interesting. Many People’s Liberation Army Navy followers have asked why China would be interested in purchasing so many units of a submarine that Russia has not even accepted into its own service.

Typically, China chooses to only purchase mature systems that it can quickly induct into service. It also appears to many people that Chinese submarines are catching up to their Russian counterparts after the launch of a mysterious new conventional submarine in 2011. But the reality is that Chinese submarines still have a way to go in stealth.

As part of this deal, China will be getting transfer of technology along with local production for two of the four submarines. On top of that, some unreported Chinese subsystems will be going onto these boats. Knowing all of that, what is China providing as part of this submarine and what is it interested in?

The currently mass-produced 039B submarines are already equipped with air independent propulsion system that can be installed on the Chinese version of Lada submarines.

China could install its own sonar system and combat systems onto a Lada. China has also installed its own sonar on Kilo submarines. What China wants is the Lada’s advanced design and noise insulation technology.

From the Lada, China could learn how to design and build a single-hull submarine with conformal sonar. If we look at China’s domestic submarine, it seemed to adapt numerous features from the Lada submarine. This submarine is supposedly one of a kind, built to replace the old Gulf-class ballistic-missile test bed.

The boat is probably too large and expensive to be mass-produced. With experience from the domestic submarine and the Lada project, China could develop its next generation of conventional submarines, which bear heavy resemblance to both and uses a single hull design with conformal sonar.

For Russia, Chinese involvement could help it successfully develop the export variant of Lada to replace the Kilo. It does have to worry about China competing against it in the conventional submarine market, but that’s a trade-off it has to make to ensure that the export version of Lada gets developed in time.

Several articles have speculated on how this deal will significantly improve China’s capabilities and shift the cross-strait balance of power even more toward China’s favor. Those stories miss the point and show very little appreciation of China’s current military-industrial complex.

While these purchases will help and speed up PLA development, they are by no means game-changers. But they will improve ties between the two countries at a time where Russia constantly complains about trade imbalances.