In the eastern Chinese city of Lianyungang, a five-day exposition in early September drew delegates from 139 countries to witness what may be the most concentrated display of state security technology in the world. China, which has more than doubled its public security technology spending over the past decade, is no longer simply building these tools for itself — it is offering them to the world. From robots that deploy restraint nets to cameras that read the invisible language of the human face, the machines on display raise a question that transcends any single nation: who decides how far th