Materially, they're xenophobic, like the rest of humanity. Claiming that they're uniquely not xenophobic is racist in its own way.

They've decided before. So has Japan. But you're missing the point here. It's not about likelihood of it happening, it's about what's possible today vs possible in a changed world.

I'll try stating it another way. If the US got busy with a civil war for the next few years and I was in a leadership position of say Korea or Japan, I would be pushing for a nuclear program posthaste, because that's the only real deterrent.