Russia's Eastern Military District is expected to soon receive two major additions to its air regiment, in the form of two new Sukhoi Su-35S fighter jets, the district's press service said, Sputnik News reported Monday. The jets, upgrades of the Su-27, were slated for deployment in Primorsky Territory, which is situated in the far east of Russia between China's northern Heilongjiang province and the Sea of Japan.

The Su-35S is an upgrade of the Su-27 fighter, and for many years was a mystery to defense analysts, as different jets were pictured with the same label, according to Defense Industry Daily. After 2007, however, more information emerged suggesting that not only was the Russian Air Force becoming more dependent on the craft but that the jet was also poised to become the go-to fighter aircraft for export.

"On the world fighter market Russia’s Sukhoi is pinning its hopes, in the near future, on a substantially modernized Su-35 multi-role fighter," reads the Moscow-based Sukhoi Company's website. Differences between the Su-27 and the Su-35 could be found in the increase in its service life to 6,000 hours, a new integrated control system that would "enhance the fighter's handling capability and maneuverability," better engines and "improved stealth radar," among other changes according to the website. The Su-35 can carry guide air-to-air as well as air-to-surface missiles, among other arms.

When compared with Lockheed Martin's F-22 Raptor, the Sukhoi Su-35 costs $85 million less (the Raptor is $150 million, the Sukhoi $65 million) but has a greater range and a slightly higher long-range cruising speed, although the Raptor has a higher maximum speed, according to the data website Axlegeeks. 

Other countries interested in the Su-35 include China, which in November spent $2 billion buying them from Russia, and Indonesia, which ordered 12 of the fighter jets in November to replace the F-5 Tigers it has used since 1980.

Russia and China have previously conducted joint naval exercises in the Sea of Japan to bolster their military preparedness. At the same time, tensions have risen between Russia and NATO countries, including the United States, while China has increasingly bolstered its military presence in the South China Sea amid territorial disputes there.