Folks, most of the ex-US equipment in Vietnam has long since been retired: only the UH-1s are still in service:
Current inventoryType In serviceCombatSukhoi Su-22 36
Sukhoi Su-27 37
Sukhoi Su-30MK2 36
TransportPZL M28 (Maritime patrol) 1
Antonov An-26 30
Antonov An-2 8
CASA C-295 3
HelicopterKamov Ka-32 2
Mil Mi-8/17 87
Mil Mi-24 25
Bell UH-1H Iroquois 26
AS350 Écureil 5
SA330 Puma 14
TrainingAero L-39 26
Yak-130 14
Yak-52 36
Sources:
https://en.wikipedia.org/wiki/Vietnam_People's_Air_Force#1975.E2.80.93present_.28reunified_Vietnam.29https://en.wikipedia.org/wiki/List_of_equipment_of_the_Vietnam_People's_Air_ForceSo if we're being realistic about it, updated F-5s and A-37s are off the table. If I was the VPAF I'd be looking for the following as priority programmes:
1. Replace the Su-22s with something more modern that can carry western air-to-surface weapons. 36 x F-16s to a decent spec would be ideal.
2. Expand the maritime patrol mission, since resource conflicts with China are on the cards. Since they operate Cn-295s already, Cn-235 Persuaders or a maritme version of the -295 would seem the most painless route. If they need serious ASW capability then how about surplus Orions (if there are any) or S-3 Vikings from AMARC?
3. Replace the Yak-52 with a turboprop: Tucano, PC-9, PC-21 or T-6 Texan would be the logical options.
4. A Huey re-build would be good, but I'm not sure it's essential: they could just retire them and consolidate on the Mi-17, which they've already got far more of. A more useful helicopter buy would be new Chinooks and/or western-style gunships such as the AH-1Z or AH-64.
5. Get an AWACS capability. The Embraer-145 AEW&C is the obvious affordable choice, but the Boeing Wedgetail or the Hawkeye might be other options.
Of course, you don't have to be realistic: maybe you could re-write history so that Vietnam fell out with the Russians, didn't get the Su-27/30 and is still operating clapped out F-5s and A-37s.