@randahl I think I can prove it: there's documentation in the official memoir in a US university.
Besides that proof you'll certainly agree that a North Atlantic organization should be restricted to the North Atlantic, doesn't it ?
I'll bring that tomorrow.
In the meantime you should concentrate in minimizing russophobia.
Dear @randahl, please take a look at the following links. They aren't an official document stating that NATO wouldn't expand.
Gorbatchev was a bad politician in disguise and didn't obtained that formal promise from NATO, aka USA.
But there were informal promises from top rank USA officials, like James Baker famous "Not one inch" meaning that NATO wouldn't expand to the East.
Please take a good look at this page from the US National Security Archive:
https://nsarchive.gwu.edu/briefing-book/russia-programs/2017-12-12/nato-expansion-what-gorbachev-heard-western-leaders-early