BEIJING (AP): China's Liaoning aircraft carrier group has embarked on a realistic combat training mission in the Western Pacific, the Chinese navy said Tuesday.

In a posting on its social media site, the navy said the mission is routine, adheres to all international laws and practices and is not directed at any third parties."

However, the mission underscores the growing role of China's naval forces as Beijing seeks to supplant the US as the pre-eminent military power in Asia.

China operates the world's largest navy by number of ships, while the US maintains an edge in aircraft carriers and nuclear submarines as well as in numbers of bases and allies in the region, where the competition is focused on the strategically vital South China Sea.

The Liaoning was originally purchased as a hulk from Ukraine and entirely refurbished.

China has since added a second entirely home-built carrier, the Shandong, and is believed to be at work on at least two more.

Exercising under realistic wartime conditions has become a focus of China's military in recent years, in apparent recognition of its lack of combat experience going back four decades.