The Chinese People's Liberation Army (PLA) Air Force in the mid 2010s acquired two entirely new elite air superiority platforms, the Russian built '4++' generation Su-35 supermanoeuvrable fighter and the domestically produced J-20 fifth generation stealth fighter. These as of 2018 form the elite of an already high end fighter fleet, the majority if which is comprised of heavy specialised platforms rather than light multirole aircraft. While the J-20 has drawn more attention as the more prolific of the two fighters, the Su-35 with its greater manoeuvrability, durability and missile carriage is not to be underestimated and poses a critical threat to all China's potential adversaries.
In response to growing tensions and an expanding U.S. military presence in the South China Sea, the PLA Air Force has deployed Su-35 fighters to the region in significant numbers. With the Su-35 having proven highly effective when deployed by Russian forces to Syria in deterring U.S. military action, their elite fighters' deployment to the contested seas is inevitably highly unwelcome in the Pentagon. On February 7th 2018 the People's Liberation Army Air Force announced that Su-35 fighter jets had been sent to carry out joint combat patrol missions in the South China Sea. These were allegedly part of Su-35 pilots' training, and attempted to simulate under long distance and high sea conditions for combat operations. This could possibly signal larger deployments of the fighters to the region in future.
Xu Guangyu, a retired PLA Air Force major general and a senior advisor to the China Arms Control and Disarmament Association, noted the fast progress which Chinese forces were making with pilot training. He stated: "Apart from the most advanced J-20, a Chinese made fourth generation stealth fighter jet, the Su-35 is more advanced than other Chinese fighter jets at this moment... now we can put them into a real combat mission in the South China Sea." He noted that the induction of the platform, the most advanced Russian fighter other than the Su-57, "shows that China-Russia military cooperation is solid, mutual beneficial and reliable." The former General suggested that the Su-35 deployment was very likely a response to what China perceived to be U.S. aggression in the region - namely an incident in January 2018 when a U.S. Navy destroyer USS Hopper came within 12 miles of the disputed atoll of Scarborough Shoalentered in waters claimed by China. The former General noted: "The appearance of advanced PLA fighter jets, capable of attacking surface combat vessels in this region is sort of a reaction to the provocation by the U.S."
Russia's Air Force in 2017 modified the Su-35 to carry advanced K-35 anti ship missiles, and Chinese fighters could well also field similar platforms and pose a significant threat to U.S. Naval operations. The fighter can also potentially serve as a capable tanker hunters to impede the U.S. Air Force's ability to ferry its fighters across the Pacific by aerial refuelling - a role the Su-35 will become more capable in fulfilling armed with Chinese PL-15 or Russian R-37 missiles, both capable of targeting large aircraft at ranges well over 300km. The J-20 is also widely speculated to be tailored towards a tanker hunting role, and though fighters have been deployed near the Korean Peninsula they have yet to be seen in large numbers in the South China Sea. China's two elite fighters are set to be joined by the J-11D, China's first domestically produced '4++' generation fighter and analogue to the Su-35, by 2020. With the U.S. by contrast having no comparable '4+' or '4++' generation platforms, relying almost exclusively on its relatively small and extremely overstretched fleet of fifth generation F-22 Raptors to combat near peer threats, the balance of power in the skies of East Asia is set to shift further in China's favour.