The December-January holiday period was a memorable one for China military watchers, with two important developments.

The first was photos (see above, courtesy of Chinese Military Aviation) of what is widely believed to be the first production version of the J-20 heavy stealth fighter. Readers might recall that, back in January 2011, the J-20 created some ripples in great-power relations when the PLA decided to stage the maiden flight of the first prototype of the new jet while US Pentagon chief Robert Gates was visiting Beijing (see J-20 Flies, Gates Sighs). Since then, seven more prototypes have appeared, and now it looks like production of the finished article has begun.

Yes, the J-20 will still take some years to reach squadron service, and the jet remains reliant on somewhat dated Russian engines while China's domestic engine industry struggles to catch up. But still, this is a phenomenal achievement for what is still a fledgling industry in China, and when fielded in numbers the J-20 has the potential to substantially shift the balance of military power in the region.

The second big development was confirmation from a Chinese military spokesman that construction of a domestically built aircraft carrier is underway. As The Interpreter reported back in October, this was fairly clear from the shipyard photos anyway, but still, this announcement removes any doubt.

The spokesman's statement that the ship will displace 50,000 tonnes and have a 'ski-jump' ramp suggests that China is taking this carrier business slowly. Why? Because it means this ship will be the same size or slightly smaller than China's first carrier, the Liaoning, which was built from a refurbished Russian hull. It will also adopt the same technique for launching aircraft as that used on Liaoning: the so-called ski-jump. This is basically a ramp at the end of the carrier's short runway, giving aircraft just that little extra lift to allow safe take-off. American carriers use different technology. Aircraft are hurled off the ship at higher speed with the assistance of a steam-driven (and in future, electrically driven) catapult. This is a more expensive and complex method, but allows for bigger aircraft to take off with more fuel and/or weapons. China is thought to be working on catapult technology, but clearly it isn't ready yet.

Again, we need to apply some caveats. China is several years away from having two fully operational aircraft carriers, and even then, they will be no match for US carriers. But even with two moderately capable carriers, China will easily outrank all its regional neighbours in ship-borne aviation, and will join a select group of nations with more than one carrier in service. Again, a major achievement and a clear shift in the regional military power balance.

We'll have much more soon on China's second aircraft carrier from naval expert James Goldrick.