This is EXACTLY like the directive to returning Vietnam military not wear their uniform. This was when they were being attacked in airports on their return, and being spit on etc.
This is a MILITARY answer to a threat— not wear a uniform. That certainly serves the meme of the “civilian” police force of plainclothes, coupled with the militarization of the uniformed domestic police forces. Very odd response.
I was ACTIVE in Thailand in 61,62,63. I did NOT wear a uniform.