Sorry to rain on your "whistling past the graveyard" parade, but they are indeed physical, real, historical, and have been verified by multiple sources from the USSR and the US.
In fact, I know without a shadow of a doubt of the existence of at least one model concurrent to 1968. I heard about the details far before this ever hit the paper (1979).
Furthermore, there are multiple data points from prior to 1968 of Soviet suitcase devices including test data (multiple ignitions masked as a lager det event) as well as publically available KGB files indicating the implacement of such a series of devices.
Of course, they were crude and took a **!tload more fissile materiel than a real physicist would throw in, but they were based on a simple design that was in the World Book Encyclopedia.
Cheers!