John, 41, had previously been the head of a little-known group calling itself the Hong Kong Independence Party, where he operated the group's Facebook and other social media accounts as well as a UK-registered website.

The group advocated for foreign intervention in China's rule over Hong Kong following the 2019 pro-democracy protests.

In the wake of Beijing's crackdown on protest, the group called for the "UK and US to send troops to Hong Kong" with online posts about petitions for foreign intervention and crowdfunding for an independent Hong Kong army.

Regardless of how unsuccessful they were, this was the head of a secessionist political group, calling out for foreign invasion and raising money to physically fight the state... That being illegal is pretty normal. Even in the US, while the speech might be allowed, the latter part would not. Groups have been raided by the FBI for much less.