What is China’s People’s Liberation Army doing in Hong Kong?

Hong Kong (CNN) — Just yards from where thousands of pro-democracy supporters have been “occupying” the heart of Hong Kong’s financial district, stands an imposing gray building surrounded on all sides by a high wall — this is the Hong Kong garrison of the People’s Liberation Army (PLA), China’s armed forces.

The main gates of the base, known as the Prince of Wales barracks until London handed over the city to Beijing in 1997, are guarded by heavily armed sentries in green combat fatigues, who stand statue-like with impassive expressions 24 hours a day, seven days a week.

But despite the fact Hong Kong is a Chinese territory, the PLA garrison abides by local Hong Kong laws that emphasize the city’s considerable autonomy. In short they keep a low profile: the soldiers never come out onto the streets of the city, and there’s minimal interaction with the local population beyond the occasional open day.