On the Fact that N.A.T.O. Was Formed After WW2 as a Deterrent to Possible Soviet Aggression and soooooooooooooooo Why Did We Start Expanding it (and Thereby Isolating the Russians) Right After that Particular Empire Dissolved?

I'm gonna' go out on a limb and suggest that it likely has to do with the Military Industrial Congressional Complex (economic historian, Robert Higgs, inserted the congressional part a few years back and I've been running with it ever since) needing an enemy to keep the gravy train running......and being that Russia checks off a lot of the boxes (a remote, mysterious country with a checkered past), why not them, they must have figured.