The words "blow me" come to mind, but that I suppose is not really a diplomatic response to send to Putin
Actually there the kind of words he understands, diplomatic responses are a laugh to Putin.
Huge loss of traditional territories post-cold war. Add in economy and you can understand them a bit more.
As someone said, even China is looking forward, and frankly it looks like their even more evolved as a country than Russia. Though I'm not convinced that they have gone past the economic expansion by force method yet. I think it really depends on how long the Yanks can keep it together.
The fact that Russia is warning people of dire consequence if joining, is pure and simple stand over tactics, terror and fear, some thing the Russians are a natural at.
Putin is not an idiot, neither are the other senior Russian advisors, they know all well NATO is just a defense pact, the only threat from the west is countries that join, prosper. (well sort of prosper, a bit like three steps forward, two back)