Just like the Azmat-class ships you sold to Pakistan.
As I said, it depends on what the Vietnamese need...if they want something like a VLS SAM, we can give a bigger ship.
China has pissed us off enough that's why we're doing this in the first place.
As far as I know, there are no such plans as yet. But making it shouldn't be a big problem once IN expresses a requirement.
My guess is, a ship-based BMD should come with the next-generation destroyers we're currently working on, it's similar
to the American DD-21 concept in design.