"Both the left and the right in the US have paramilitaries (antifa, proud boys)." I'm not sure I would consider Antifa "paramilitary". Antifa doesn't have a military style chain of command, nor an organized use of firearms. While the proud boys have more of a hierarchical command structure, it's still a bit of a stretch to call them "paramilitary", there does however seem to be some shared membership with right wing paramilitary militia.