There seems to be a running narrative in Russia about the betrayal by the West. I've been looking around for information on this, as Putin has made statements about the broken promises of the West with regards to NATO enlargement. The NATO website has some good information, but they obviously have a stake in this issue. So did NATO leaders ever make explicit (or heavily implied) promises not to expand to former Warsaw pact members?
I realize this may butt up against the 20 year rule- but I'm mostly asking about the behavior of Western leaders in the time before the big NATO expansions in 1999 and 2004.
Gorbachev says "No".
There's an urban myth that NATO did promise they would not expand east. Those involved in post-Soviet discussions with western nations in the 90s do not confirm the story.
The closest thing would have been the clause in the 2+4 contract to only station German troops outside of the NATO command structure in Eastern Germany, as long as Soviet troops were present there. Foreign NATO troops are never to be stationed in former East Germany, according to article 5 of this contract. At that point, the Warsaw Pact (as well as the Soviet Union) was still intact though. I'd be surprised to hear that the Soviet leadership in 1989/1990 gave any thought about the possibility of Warsaw Pact nations wanting to join NATO.