Russia was never “imperialist” in the way the west is. They never had an Empire as the Soviet Union. Russia cannot become an empire by invading other countries, imperialism functions by massive financial capital to extract from the global south. Russia doesn’t have the capital for that, and is more industrialized than western countries that need it to stay afloat.

As for NATO, it’s to ensure western imperialism stays intact. The US is the main beneficiary, but western Europe participates because they also profit from brutal exploitation of the global south.