I have to disagree with Blashy a little here, I don't think it would have been a Dieppe. This could depend on when and how they hit the US, the earlyer they landed the more ground they would have been able to take, remember we would have been fighting on 2 fronts and one of those would have been the US. I think at first there would have been a lot of panic so they would have made some inroads but we would have pulled ourselves together and drove them back into the Ocean. We got a little lucky with Midway even with breaking the code we could have still lost that battle. If those carriers were not rearming when we hit them they could have still had 3 carriers and they would have had a better chance to find our carriers and destroy them. Of course if they had just landed on Hawaii it would have been a long, long war for the US.