It’s a myth, the west never promised Russia that they won’t expand eastwards. Shevarnadze (former Soviet foreign minister) said that the West never made such a promise, so did Gorby. It is a myth, a fake.
Poor Russians: “The West lied to us”. Oh the moral indignation, “we’ve been wronged, now we can go pillage and murder anyone we like.”
The Russians need to move West, as Siberia in the East is slowly becoming mostly populated by Chinese. Besides, when the Russian Czars looked to Europe, wasn’t that supposed to be a “good” thing?