According to Qian, in Hong Kong Beijing has final power over foreign affairs, defense, and any matter related to Taiwan. Thus, while the hanging out of ROC flags is a purely private matter Hong Kong people cannot but be wary that their activities can be labeled by Beijing as "promoting two Chinas."
固然港九國慶懸掛國旗多屬民間自發，但外交、國防、涉台問題詮釋權在北京，不是沒有可能被解釋成「搞兩個中國」，這點香港人不得不防。