All that doesn't matter when there is a nuclear war at hand.Yep, you can build, Japan can also, but USA will not allow, they will embargo you like North Korea, your economy will collapse.
Nobody asks for nukes; all who want one build one themselves.Many problem can happend if South Korea have Nuke. Japan -Taiwan etc..will ask for it also
In exchange, the US guarantees a nuclear retaliation against anyone, China inclusive, who uses nukes against them.Hehe, Trust is the Trust, they won give S.Korea-Japan-Taiwan the right to make Nuke.
There is no chance of US not honoring that nuclear security guarantee. Why? Because not honoring that guarantee dissolves NPT and turns every country to seek their own nuclear weapons for self-protection. Worse yet, Korea still retaliates with its own nukes a month later, so not nuking China now doesn't prevent it; it only defers the nuclear retaliation by a month.
That's why Vietnam is a 3rd world country.I tell you one thing, To VNese thinking : All kind of treaty, agreement is just Toilet paper only
And face UN sanctions, which destroys Vietnamese economy.So, good luck for S.Korea future, we VN already has the right to enrich Uranium in our own soil