To quote a famous meme and made it more elegant:
They are free to test that assumption at their own convenience and stay around to find out if it meets their expectations.
The issue now is that this is a genuine surprise attack on American soil, if this doesn't jump start the industrial jump start needed that I'll be damn.
Great, the Japanese has started The Great War and now the US Navy is missing it's most modern of defences... time to send the Coast Guard out with depth charges folk! Modern Sonar will make things easier to hunt.