>What actually happened is that, as part of the deal to reunify Germany, Russia had been given assurances that NATO would not be expanded in its direction
That is an old leftist myth that has now found its way to some conservative circles. Bush, Baker, Shevardnadze and Gorbachev have all denied it. Here is a recent denial of this promise ever been made from Gorbachev.
http://rbth.com/international/2014/10/16/mikhail_gorbachev_i_am_against_all_walls_40673.html
RBTH: Why didn’t you insist that the promises made to you – particularly U.S. Secretary of State James Baker’s promise that NATO would not expand into the East – be legally encoded? I will quote Baker: “NATO will not move one inch further east.”
M.G.: The topic of “NATO expansion” was not discussed at all, and it wasn’t brought up in those years. I say this with full responsibility. Not a singe Eastern European country raised the issue, not even after the Warsaw Pact ceased to exist in 1991. Western leaders didn’t bring it up, either. Another issue we brought up was discussed: making sure that NATO’s military structures would not advance and that additional armed forces from the alliance would not be deployed on the territory of the then-GDR after German reunification. Baker’s statement, mentioned in your question, was made in that context. Kohl and [German Vice Chancellor Hans-Dietrich] Genscher talked about it.
I presume this means that you can’t support the assertion that Russia was offered NATO membership, since you ignored the question?