What inanity! If the early-warning system is connected to the internet, there's this huge chance of somebody else connected to the internet being able to trigger an early warning.
Even if it's offline until the moment -- and only during the moment -- it needs to login and send the tweet, there are so many possibilities as far as hacking the early warning system.
It must have sensors of some kind, and sensors can be quickly and easily fooled. And if the sensors aren't so vulnerable? There are obviously some people attached to the system who can also be quickly and easily fooled.
This is even worse than electronic voting! Seriously! I think we should be petitioning the local government of Yokohama to cease and desist!
As another user here joked (and I find the joke hilarious), "maybe my Tweet-monitoring Nuke launcher was a bad idea..."
Well, the Tweet doesn't have to trigger a chain reaction of nukes to have potentially dangerous, even deadly side-effects. And certainly the people of Yokohama don't deserve those minutes of accelerated aging over the supposition that nukes are literally right on their way.