Sukhoi Su-35 fighter jet
A Sukhoi Su-35 fighter aircraft takes part in a flying display, during the 50th Paris Air Show, at the Le Bourget airport near Paris, June 20, 2013. REUTERS/Pascal Rossignol

China received four Sukhoi Su-35 Flanker-E fighter jets from Russia, according to reports. The aircraft were delivered in late December in southeast Chinese Guangdong province’s Suixi Airbase — the nearest Chinese airbase to the South China Sea.

In 2015, China confirmed that it signed a $2 billion contract with Russia for 24 Su-35 fighter jets after five years of on and off negotiations. State-run China Daily reported, citing the People’s Liberation Army’s website, that with the commissioning of the J-20, China’s domestically developed stealth fighter, Russia realized that the Su-35 “will lose its value on the Chinese market in the near future” following which it wanted to complete the Su-35 deal. The Su-35 is Moscow's most advanced fighter aircraft in use.

For several years, Beijing has reportedly been trying to manufacture an indigenous fighter jet engine. However, the East Asian country’s program has been marred by technical problems. China’s stealthy Chengdu J-20, single-engine Chengdu J-10 and Shenyang J-15 carrier borne jets run on Russia’s Saturn AL-31 engine.

Andreas Rupprecht, author of three books on Chinese military aviation and industry, told Defense News that one of the reasons Beijing is seeking the Su-35 is to gain access to modern Russian engine technology — particularly the Saturn AL-41F1S (117S) afterburner turbofan engine that helps gives the Su-35 directional thrust ability.