The entire US embargo policy against Cuba, Iran, North Korea etc. is
silly regardless of the period of issue of stamps. USA turned into the
USSR and DDR, which also hid their heads in the sand and did not
recognize stamps of the 3rd Reich, fascist It...
This may be the result of using alien agressive glue which changes color
gradually and partially.It was common in USSR in 1920's-80's, when
so-called "chancellery glue" (liquid glass)widely used at post offices,
so many stamps were spoiled.
