[jacobsievers]

The "promise" wasn't exactly as suggested in the quote. It wasn't agreement, but part of a back-and-forth thought problem. Gorbachev was asked if he preferred a reunited Germany to be a member of Nato and thus constrained by that alliance, or a free-actor--implying that an unaligned Germany would return to it's expansionist ways. Gorbachev followed up by asking if Nato would expand further east and Baker said no. But this was all part of the hypothetical posit.

Edit: Further, Gorbachev himself stated that he believed nations should be free to make their own decisions on whether to join Nato or not.

Edit: Looking for source led me to an interview with Gorbachev where he claims this "promise" never happened at all: https://www.rbth.com/international/2014/10/16/mikhail_gorbac...