That can be done with the many territories the United States has near Vietnam and elsewhere. New states will both require much manpower to make the land more commercial (hotels, restaurants), and will make the United States the only globally-spanning country in the world, since Vietnam is over the dateline. Veterans might not like the idea, having fought in Vietnam, but they have already helped us by going there once. They can stay here, now.
Vietnamese islands and other areas we already have possession of are currently costing us more than they are paying back. Making them into true states would make people feel freer to travel there for vacations and business. They would require people to work in hotels and stores there.