Russia and Ukraine

[BrianSoddingBoru4]

Wouldn't that promise (can't find a formal agreement on that) have been made to the Soviet Union, not the Russian Federation?

Yes, that's a good point.

But since it was a promise made concerning the break-up of the USSR, Gorbachev clearly expected it to last. It was kind of a deal: you give up your claim to these former territories, and we'll keep our military alliance out.

Two things: 

First, it’s not a ‘good point’. Under international law, the Russian Federation is the legal successor to the USSR. The means all treaties signed by the Soviet Union are binding on the RF.

Second, both Baker and Kohl called it ‘a talking point’. It doesn’t appear in any treaty. Kohl said he discussed the ‘no eastward expansion’ with Gorbachev, but explicitly told him that he couldn’t speak for NATO as a whole. In short, there was no promise, binding or otherwise.

Boru