Vietnam veteran's ID tag returned to North Dakota widow after found in Russia

The speculation was battlefield souvenir

I have heard that certain soldiers, pilots especially were kept in special detainment centers in North Vietnam where their MOS skills could be learned from them. Also the Russians were looking for slave laborers too and since WWII had in fact shipped thousands of captives from that theatre of conflict to their prison farms and it was noted that several G.I.'s were seen boarding trains and their patches and insignia were removed from their uniforms and left on loading docks all over the world.