Imperialism is a lot more complicated than that. The ruling classes of Canada, the EU countries, Japan, and Australia are mostly happy with the present arrangement, of which they are an integral part. Sure there are family quarrels, as in the run-up to the Iraq war, but the system is pretty coherent and functional. The second-tier imperialist powers can occasionally get all high-minded and look down on the nasty practices of the US, but they're still part of the system. There's a weird narcissism among American leftists who want to see Washington in this Coxian way.
Doug
&&&&&&&& CB: There is a tradition ( that shall remain nameless) that emphasizes opposing one's "own" imperialism without endorsing other imperialisms. That seems sort of the opposite of narcissism. More criticism-SELF-criticism. Also, I think there is the notion that one has the best chance of political action in one's own country as opposed to another country. There's even the older idea that each working class must settle accounts with its own national bourgeoisie, first.
For example, we might criticize Israel, but we must always think again: our job is to emphasize criticism of the U.S. and its control of Israeli imperialism.
In this case, Russian , Venezuela and Iran are not imperialist countries, are they ? They have no colonies, for one thing.