Not far from Central Hong Kong, the city's busiest commercial district, stands the regional headquarters of the Chinese People's Liberation Army (PLA). Though most of the 28-story building sits empty, a glaring PLA logo still hangs from its roof, lighting up the Victoria Harbor below. The scene offers a stark contrast to the same view two years ago, when the skyscraper -- then unadorned -- served as a symbol of China's unobtrusive presence in Hong Kong. Whether intentionally or not, that subtlety is now gone, as is Beijing's iron grip over the region that has long bucked its rule....