US put restrictions to inspect Alaska and Hawaii. This is much more serious and unequal than closing Kaliningrad region, as the latter is quite small in territory. Nevertheless, Russia was OK to continue.
Then came business as usual: when the USA want to break any treaty, they start with blaming the other side in all possible sins.
Now it looks like it makes little sense for Russia to continue this "business" with European NATO member states. Proposed "non-disclosure for 3rd parties" sounds laughable. Uncle Sam can always take what he wants from his subordinates
IMHO, I do not see any tragedy in burying this agreement by the US. With current satellite capabilities planes look a little bit retro.