you don't believe in supporting our great military, sir?
how unpatriotic.
Your hook won't catch anything.
because our military was superior to theirs
Not really the US military of the 1930s was still using mostly weapons and equipment from the first world war. Were talking about bolt action rifles, brodie helmets, large heavy water cooled machine guns that were meant for trench warfare, there weren't that many tanks and even the ones we had were outdated and outclassed by the Germans.
However an invaded the united States is no easy task since we are big and vast country. It would require a vast amount of wealth, resources, and man power to invade the US. Troops and equipment would have to be shipped over seas and japan already had fighting going in China, plus they had forces defending the pacific islanders. Even then if all the Axis powers invaded the US, they would not be welcomed by any one. Which would mean that anyone with a gun would take shots at them and go into hiding to wear down the invaders morale while the military sends to make into the ocean. There is also a book on it called No Clear and Present danger.
So basically too costly and expensive to invade the US for numerous reasons. The Japanese did invade Alaska and the Germans sent a commando unit to sabotage US production. However the Japanese left because Alaska was in winter and the Commandos surrendered to police.