Russia Ukraine war, page-19067

None of that represents imperialism.
Most of the "annexations" you mention came as a result of Russian victory over imperialist Germany in WW2.
After German imperialism attempted to occupy and colonise USSR , the red army chased them all the way back into Germany and just setup all those east European countries as buffer states.
It was defensive move not imperialist.
The leading NATO powers are imperialist powers, not russia.
as explained here - https://www.wsws.org/en/articles/2022/04/05/lett-a05.html