My impression is that the Chinese civilian leadership is letting the military probe to discover the extent to which territory is free for the taking at minimal expense. The appropriate historical analogy would be the expansion into Indian territory that was part of Manifest Destiny during the winning of the West. The moment a serious clash ensues, they will pull back, hard, on the reins. Because the point of the endeavor is low cost expansion, not a military clash that costs trillions of dollars in lost military equipment, lifetime pension payments to hundreds of thousands of grieving widows and parents, trade losses and tit-for-tat economic warfare.
China's moves have nothing to do with Marxism-Leninism - China's economy is privatized with the exception of a number of state-run enterprises, and even those are run as profit-making enterprises, with executives paid and promoted based on the amount of money these enterprises make (although nepotism is a huge factor in HR decisions). Ultimately, China is resuming its ancient habit, prior to its 200 years of relative weakness, of taking territory from its neighbors whenever it can do so at minimal cost. Because China's traditional weltanschauung sees the world as composed of current Chinese provinces and future Chinese provinces, with or without their current inhabitants, depending on their willingness to submit to Chinese rule.