1-3 million? That seems like a pretty big range of uncertainty. What are your sources?
[1] http://www.jpolrisk.com/brainwashing-police-guards-and-coerc...
[2] https://www.reuters.com/article/us-usa-china-concentrationca...
[3] https://www.nytimes.com/2019/05/04/world/asia/trump-china-ui...