Yesterday at the Zhuhai Air Show, China's air force officially unveiled its worst-kept secret, the J-20 stealth fighter.

What is China hoping to achieve by showing off this new weapons system? In earlier times China would have waited until a new fighter entered squadron service before even acknowledging its existence, but that has begun to change in recent times, with the new heavy transport plane, the Y-20, unveiled at the Zhuhai air show in 2014. Partly this is a reaction to modern circumstances - in an age in which everyone carries a camera and has a social media account, it is difficult to keep a new jet fighter a secret.

That has certainly been true for the J-20, and in fact Chinese authorities clearly use phone-wielding military enthusiasts - China's accidental spies - as part of their information operations.

Yesterday's official unveiling reflects justified pride at the fact that China will soon become only the second country to put a so-called 'fifth-generation' fighter into service (the J-20 is in low-rate production and will likely enter squadron service next year). America is of course first with the F-22 Raptor and F-35 Joint Strike Fighter, and Russia was supposed to be second with its T-50, but China has leapfroged the Russians.

Mind you, the J-20 is powered by Russian engines, and most pundits assess that Chinese aero engine technology is not only well behind the US but Europe and Russia too. The J-20 is also likely to lag the US and Europe in sensors (radar, infra-red etc) and data fusion - that is, making the flood of information from onboard sensors and other aircraft digestible to the pilot.

The J-20 is probably superior to anything currently being fielded in the Asia Pacific, but whether it matches the F-35, which Japan, Singapore and Australia will field in coming years, is open to question (one American general says it's not even close).

Beyond specific capabilities, the J-20 represents China's ambition to reduce its reliance on foreign military partners and eventually make all weapons systems at home - the Zhuhai Air Show has also featured other Chinese jet fighter designs, helicopters and numerous new drones. But in fact, this ambition extends beyond military aviation into the civilian sector, with China planning to build its own large passenger aircraft. The first will be the C919, in the Boeing 737 class, but bigger jets will follow.

Photo courtesy of @CombatAir.