Humans are stupid

Then - Admiral Yamato - "You(Japan's Emperor/other military officials) cannot invade the US mainland. There is a rifle behind every blade of grass."

Now - Terrorist - "The US is disarming themselves! ALLAH AKBAR!"

I would never own anything as dangerous as a firearm <VBG>.

You nailed it. The question is not when but who will invade a weak America first.