Umm...the surprise attack at Pearl Harbor might have had a little something to do with it.
We also had military bases in the Philippines and on Guam that were likewise attacked.
Let's not forget Hawaii! The US overthrew their kingdom and annexed it; the Clinton Govt even apologized for it in 1993. It wasn't even a US state until 1959!Guam and the Philippines were products of American imperialism, along with Cuba and Puerto Rico. The nerve.
So for them to be "outraged" at it being attacked would be like if Japan was outraged if one of their territories in China (say, Manchuria?) was attacked.
Oh, wait....