Or are you referring to Crimea? All I can say is that someone let them in due to the relative bloodlessness of the annexation.
As for Brexit, remember that the USSR also had a clause in its constitutions that ostensibly permitted its soviet republics to “freely secede”.
Like Poland?
Man are you out there on a limb...
A tank division is rolling down your streets, and you don’t fire a shot.
To you, this is evidence of an open invitation.
If it was an invitation, why were tanks even necessary.
Pull in cars will new political figureheads. End of story.
There would be no need of Tanks, no need of trucks, no need of troops..., hey we were invited in.