In fact, the US media
did side with Japan as their imperial spread started. While the Japanese sneak attack against Pearl Harbor is well known as a Japanese outrage, slightly less well known is the Japanese sneak attack against the Czarist Russian fleet at Port Arthur (now Korea) in 1905. At the time, the US media went wild, lauding Japan for its unwarned, surprise attack against Russia before Japan declared war. It was looked upon as a brave rout against the encroaching Russian octopus in the far east.
Surprisingly, 36 years later, the press was distinctly less amused at Japan's "heroic" antics, but they seemed perfectly happy to look at things from their side, before.