Mussolini was a Socialist. Socialism is the root of Fascism. The only reason Fascists didn’t approve of Communism was its Internationalist, rather than Nationalist orientation.
Ironically, Stalin also rejected Internationalism, for “Socialism in One Country”, his foreign policy goals were basically no different than that of the Tsars.
I think it can be successfully argued that Stalin’s Communism\Socialism was actually a Russian native Fasicism - a Russian form of Nazism (National Socialism). Same form China!
More proof those who go around shouting Fascist, haven’t a clue what it is!