Although the JASDF will not be a strategic deterrent for China once it is equipped with the F-35A fighter, the addition of the plane will still have an effect on the Chinese air force and on its strategic anti-aircraft defense systems. The foremost threat it poses is its stealth capabilities, which represent a revolutionary upgrade from third-generation fighters and will shake up the early warning and sensor systems of air combat. The F-35A reduces the RCS of third-generation fighters from several dozen sq m to just one tenth to one hundredth of a sq m, which is enough to half the distance at which it can be detected by radar. This puts pressure on Chinese early warning craft to increase their coverage to prevent the F-35A making use of blind spots. It also demands a much more concentrated deployment of anti-aircraft weapon systems or an upgrade to their anti-stealth capabilities. Chinese air force formations will also have to adjust their formations, as although the F-35 hasn't substantially improved on the maneuverability of third-generation fighters, the F-35A has a tactical advantage over Chinese third-generation fighters, due to its ability to see the battlefield more clearly. This means that the PLA Air Force will have to put fourth-generation J-20 fighters to the front of formations, in order to discover the F-35A fighters as soon as possible. These J-20 fighters can then intercept the F-35 fighters and push them out of Chinese airspace. Given the severe drop in RCS with fourth-generation fighters, adding concentrated deployment of early warning aircraft and radar is a bottomless pit, as no country has been able to make up for the shortfall in their early warning and anti-aircraft defense systems. The only effective means of dealing with this state of affairs is to develop a fourth-generation fighter with similar capabilities, posing an equal threat to the enemy.
The J-20 has already undergone several test-flights, suggesting that China's fourth-generation fighter is almost complete and is on the brink of entering the manufacturing stage. After the final version of the plane is fixed and undergoes test-flights, manufacturing can begin, which means the J-20 will be deployed by 2017 at the earliest and by 2019 at the latest.
If the J-20 is manufactured at the rate of one regiment per year, then by 2025, 5-7 regiments will be equipped, with around 120-170 planes, which makes up around two air force divisions. The US only has 187 F-22 fighters. With China's J-20 fighters in development, as well as the sheer numbers of third-generation fighters, forming its main strategic combat force, along with early warning aircraft, electromagnetic interference systems and airborne warning and control systems, China will have a clear advantage over Japan in any potential air battle. If the J-20 is equipped with China's fourth generation active electronically scanned array radar, and this equals the APG-77 with which the F-22 is equipped, the aircraft will be able to detect an F-35A head on at a distance of 50 km, whereas a F-35A will only be able to detect a J-20 head on at a distance of 20-40 km, giving the J-20 the advantage. The J-20 has similar capabilities to the F-22, including supercruise, electronic countermeasures (ECM) and supermaneuverability, giving it an advantage over the F-35A under all battle conditions.