This is the standard lie from the Trotsky wing of the Bolsheviks. If you are a socialist and you want global revolution -- international socialism -- then you are Leftwing. But if you are a socialist and you want to focus on revolution in your own country -- national socialism -- then you are rightwing.
Note that Trotsky was a Globalist/International Socialist. Stalin was a National Socialist. Hitler was a National Socialist. There's actually no "rightwing" anything in this story.
Succinctly stated, my FRiend.
Should be required reading for wannabe "citizens of the world" (among others).
Hitler and Stalin greatly admired each other, despite being enemies.