China’s latest stealth fighter, the J-20, is serving in the People’s Liberation Army air force, according to state media. Military insiders said the appearance of J-20s in the air force was meant as a warning to Japan and South Korea, which are expected to buy US F-35 stealth fighters now that China has equally advanced warplanes. Video footage aired by CCTV yesterday showed J-20 fighters alongside PLA Y-20 transport planes and H-6K bombers. The broadcast did not say how many J-20s were operational. America’s F-35 fighter jet vs China’s J-20: which is better, cheaper, stealthier? The report said the new aircraft had joined joint drills with troops, rocket forces and the navy. A source close to the PLA said the J-20s were all equipped with home-made WS-15 engines, but because the engine had not entered mass production, only a few J-20s were available for service. “There are still a series of technical problems that need to be tackled [on the J-20], including the reliability of its WS-15 engines, [and the plane’s] control system, stealth coat and hull materials and infrared sensor,” said the source, who requested anonymity. But with the US deploying a batch of F-35s in Japan in January, and South Korea planning to have 40 F-35s in 2018, “it’s urgent for China to show off its achievements as soon as possible”, the source said, adding that more J-20s would join the PLA this year. Chinese military websites showed pictures last December of J-20s with serial numbers indicating that at least three types of the stealth jets had joined the air force since last year. The J-20 made a two-minute public debut at the opening of Airshow China in Zhuhai in Guangdong province on November 1, flying over the show each day after taking off from an airfield in nearby Foshan. Visitors were not permitted to view the aircraft on the ground, sparking speculation that the home-made aircraft was falling behind its production schedule. The doubts were countered by air force chief General Ma Xiaotian one day after the jet’s maiden flight. Ma said development of the J-20 fighter jet would be sped up and it would be put into operation in the air force soon. That claim was countered by air force chief General Ma Xiaotian one day after the jet’s maiden flight. Ma said development of the J-20 would be sped up and that it would be put into operation in the air force soon. Designers of the J-20 claim the fighter represents a “big leap forward in terms of the capabilities of the PLA”. The aircraft has a longer range, more internal fuel capacity and a larger weapons capacity than the US F-22 and F-35 fighters, the designers say. Can you differentiate China’s J-20 and J-31 fighter jets? Taiwan’s defence minister and air force chief can’t Western military experts said the shape of the J-20 copies the US F-22, but that many of the internal details of the aircraft remain a mystery. Macau-based military observer Antony Wong Dong said China’s J-20 still had a long way to go to catch up to the F-22 and F-35, with engine development still the core problem. “Not only the J-20 but China’s Y-20 transport plane are facing the same problem, that the WS-18 is still not in mass production,” Wong said.