The last major ‘military’ clash China was involved in was not over land, but in the sea with Vietnam in 1988. Chinese and Vietnamese patrol boats engaged in standoffs as recently as a few months back over the Paracel Islands. Building up your land and air forces do little to strike at China’s Achilles Heel-its need for Middle Eastern oil. A handful of subs make a difference to that.
A little research indicates that BP still has an interest in production, there.
With your mention of China's oil problems...