Beijing says People’s Liberation Army is a ‘pillar of stability’ for Hong Kong
https://www.scmp.com/news/china/diplomacy/article/3020287/beijing-says-peoples-liberation-army-pillar-stability-hong
People's Liberation Army has already been in Hong Kong since handover from UK to China. But, so far, it doesn't seem to be mobilized during protests.
I guess the army is not good at battling with protesters in downtown of Hong Kong, with narrow roads, high buildings, steep slopes.
So, the Chinese government hires gangsters and general people to disturb protesters.