I believe that ground units used metrics. A Vietnam Vet SEAL friend, in describing an engagement to me, used the word “meters” regarding the range at which he fired a grenade.

In aircraft, we used English units, but as far as I know those were universal world wide at the time. So on our radar, we measured Nautical Miles. Our altitude was in feet (usually below 100 – try that over the pacific for a few hours some time).

Hence I see nothing odd in Kerry using meters for brown water Navy service. Presumably the swifties were coordinating with ground forces, in a country that used metrics.

Certainly I first bacame aware of the word “klick” for distance in regard to Vietnam – it means kilometer.