"The Americans promised that Nato wouldn't move beyond the boundaries of Germany after the Cold War but now half of central and eastern Europe are members, so what happened to their promises? It shows they cannot be trusted."
People never quotes Gorbachev conclusion in that article, since he denies your denial:
"The decision for the U.S. and its allies to expand NATO into the east was decisively made in 1993. I called this a big mistake from the very beginning. It was definitely a violation of the spirit of the statements and assurances made to us in 1990. With regards to Germany, they were legally enshrined and are being observed."
https://rg.ru/2014/10/15/gorbachev.html
> Mikhail Gorbachev: The issue of "NATO expansion" was not discussed at all and did not arise in those years. I say this with all responsibility. Not a single Eastern European country raised it, including after the termination of the Warsaw Pact in 1991. Western leaders did not raise it either.
> Another question was discussed, which we raised: that after the unification of Germany there would be no advancement of NATO military structures and the deployment of additional armed forces of the alliance on the territory of the then GDR. In this context, Baker's statement mentioned in your question was made. Kohl and Genscher spoke about the same.
In summary: no discussion, no promises, no agreement.
You misinterpret "violation of the spirit". He hoped for better future than currently is, a future of peace and cooperation that would not need Eastern Europe clinging to NATO for security from Russia and its puppets. Ideally, NATO would've become obsolete and Russians would be enjoying the same quality of life as Germans are. The reality is much bleaker and that 1990 spirit is dead. That's what he meant.
You idea about a misinterpretation of Gorbachev's words "violation of the spirit" is contradicted by the rest of that sentence, binding the spirit to the words of the Treaty of 1990.
The very promise to Gorbachev that NATO would not expand eastward is, as he says, legally enshrined in that treaty: "Foreign armed forces and nuclear weapons or their carriers will not be stationed", though only for the east "part of Germany". At that time it would have been unthinkable to discuss any further expansion of NATO.
To blatantly deny this fact is "modern-day NATO propaganda". But you are welcome to claim, that "no discussion, no promises, no agreement" about this was ever written in treaties - if you every time remember to add "except for the part about eastern Germany, where that promise is very well documented".
> At that time it would have been unthinkable to discuss any further expansion of NATO.
Exactly. It wasn't discussed, nothing was agreed upon or promised to anyone.
Most Eastern European countries that later applied for NATO to secure themselves from increasingly hostile Russia didn't even exist as countries at the time, nor did Russian Federation. It was a totally different time and suggestions of promises about NATO membership availability to Eastern Europe are an anachronism.