I recently found an old landmine warning sign for sale in a kind of thrift shop, and it made me remember essentially everything I know about my grandmother's uncle-- that he was conscripted into a forced labor battalion, and part of their job was clearing landmines. (He was killed doing this.) For some reason I remembered that again today, but this time in conjunction with the GAR penal battalion red triangle meta.
Just a coincidence, but look what else is symbolized by a red triangle:



Just a coincidence, but look what else is symbolized by a red triangle:
