Horseshoe theory

Russia has for years fostered close ties to various extreme right movements and has its own neo-Nazi groups. Russia has served as a meeting point for extreme right populists. For example, in 2015, representatives of several European parties participated in the "International Russian Conservative Forum". Extreme left, on the other hand, doesn't seem to be able to let go of its old illusions of Russia as an anti-imperialist power.

See e.g., Atlantic Council's Reports "Kremlin Trojan Horses"

Nr 1 https://www.atlanticcouncil.org/in-depth-research-reports/report/kremlin-trojan-horses/

Nr 2 https://www.atlanticcouncil.org/in-depth-research-reports/report/the-kremlin-s-trojan-horses-2-0/ 

Nr 3 https://www.atlanticcouncil.org/wp-content/uploads/2021/02/The-Kremlins-Trojan-Horses-3.pdf