If I remember my Cold War reenacting research correctly, the boots shown in the CRL are East German military issue. The buckles at the top make them Bundesmarine boots, specifically, like the ones shown in this picture. The ones without buckles are NVA issue (think Soviet DDR, not Vietnamese lol). There was a lot of variation in NVA issue items over the years due to Soviet Russian oversight, but the Bundesmarine versions look the most accurate to me.
(The sole in this picture is probably post-1991. I think the Soviet soles were brown leather with visible hobnails.)
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