While Vietnam is an economic basket case and will welcome “investment” from just about anyone, I’d think they would nix a Russian military base because of the joint Chicom/Rooskie naval exercises a couple of weeks ago. They might let them build some commercial ports and land transport hubs, though.
The Cubans, and Venezuelans, however, don’t care what Obama thinks, so bases there are probably a done deal. Heck, the Venezuelans have already let Iran build facilities there.
Vietnam is an economic basket case