The U.S. has been gunning for Russia for centuries

Technically one century but sure, I don't deny that the US attitude towards Russia stems from imperialism.

It's borderline racist to claim that Russia is imperialist

"It's borderline to say Russia has reached the final stage of capitalism, with the financialization of the economy and the concentration of capital in the hands of a few oligarchs" I really don't see how it's racist to say that.

when you claim that Russia is imperialist for defending it's people from a decades-long siege that is generations old

Establishing a continuity in "Russia" and the reasons for the US hostility towards it for the past 100+ years is absurd. The reasons why Tsarist Russia was expansionist (although not imperialist since it was barely industrialized), weren't the same as why the USSR invested in military and the US was hostile to it, and aren't the same as to why modern Russia invests in military and why the US is hostile to it.

for defending it's people

And I don't claim that Russia is imperialist because it engages in warfare, that's not my criteria. The USSR engaged in warfare and Afghanistan and it wasn't imperialist, the argument could be made that something relatively similar is happening in Ukraine now. My point as to why it's imperialist is the consolidation of capital in the hands of a few, and the financialization of the economy. The EU is also an empire in this regard. It's harder to say for China given the wide state control over the private companies. I really fail to see how comparing highly developed capitalism in country A with highly developed capitalism in country B is racist of a State Department talking point.