You're wrong. There was indeed never anything "official", but high-level diplomats (such as the US Secretary of State) did promise as much behind closed doors.

You're wrong. There was indeed never anything "official", but high-level diplomats (such as the US Secretary of State) did promise as much behind closed doors. See https://nsarchive.gwu.edu/briefing-book/russia-programs/2017-12-12/nato-expansion-what-gorbachev-heard-western-leaders-early https://nsarchive.gwu.edu/briefing-book/russia-programs/2017...