Multiple imperialists competing with each other is the description of Europe. China hasn’t been imperialist for over a century and even when it was an empire it was not a global spanning project and it was ended by the European empire. The European empire won. They are the empire. The USSR wasn’t imperialist, they were anti-imperialist. The revolution literally rode in on the idea of the Russian empire being defeated in WW1 - it was the revolution’s explicit program that Russia should lose the war, they would depose the imperialists, and then they would establish independent republica for all of the occupied people’s and form a union of independent republica with the constitutional right to secede.

Yes, by the time Brezhnev came to power the USSR was not only deeply reactionary and actively building the conditions to end the Republic, they also started to position themselves to become a partner with the North Atlantic Empire, but the North Atlantic Empire was not interested in that, they wanted total subjugation. Gorbachev worked with the North Atlantic Empire to achieve that through dismantling the union and implementing liberal shock therapy which allowed for local oligarchs to concentrate wealth but also allowed the West to extract huge amounts from them as well. And it got Russia nowhere. They did not join the empire, they did not build a new empire, they simply became subjugated in a neoliberal relationship with the empire.

I know you want to pretend that people with large militaries are imperialists and that you can possibly hold the position that everyone who is fighting the empire is imperialists because they’re psychologically imperialists even if the only active conflicts they have are border disputes that are deeply tied to the force projection apparatus of the global spanning mass murdering empire, but it’s just pretend. It’s not reality.