I remember all the whining about "NATO bases on our borders!!!" on Russian news back in 1999 when Poland joined. And then again in 2004 when the Baltics joined. It was all the same stuff then as it is now - about how they were just prepping the beachhead for those tank columns that would eventually drive towards Moscow, how NATO nukes would be stationed there allowing for a surprise decapitation strike etc. None of which came to pass in the years since, unsurprisingly.

In any case, what does "supposed to be a buffer" even mean? Supposed by whom? Ukraine certainly didn't sign up for that.