In America it should not be "fine" to ban first and ask questions later. That's preposterous and sets a horrifying precedent. We're a trading nation, not a banning nation.

Also a free nation.

For certain definitions of free.

I think it's fine to incarcerate all Japanese first and ask questions later. If we find out later they aren't really spies and we shouldn't have done it we'll just release them. /s

I think it's fine to incarcerate suspected terrorists first and ask questions later. Since the courts most definitely won't allow that on American soil, we'll incarcerate them in Guantanamo. If we find out later they aren't terrorists we'll just release them. /s