Jeez, people can sure be real pathetic. Why bring war into this? The United States has been at war with numerous countries throughout history, but that doesn't suddenly mean that just because we were at war with a country in the past doesn't mean we get to laugh at them when they suffer. Think about it, the United States was at war with itself in the past, but we don't laugh at ourselves when some sort of natural disaster causes massive damage to the country.
Regardless, Japan may have bombed us in the past, and we may have bombed them back, but that doesn't mean Japan is a hateful country. Japan is an awesome country that supplies half of the electronic supplies that you've come to use today. The United States has a good thing going with Japan, and when they are in a time of disaster, we try to help them just like they'd help us if we were to fall under a disaster.
So, don't bring World War II into a serious discussion like this, because it truly is pathetic.