Why were Japan and the United States fighting in World War 2?

After the Sino-Japanese War of 1894, Japan felt it was not receiving it's fair share of the spoils of war. In 1904 this led to a war against Russia. In that treaty in 1905, Japan felt it wasn't getting it's fair share of the victor's portion, and continued to build up it's military for the next war. In WWI, Japan was an ally against the Central Powers (Germany, Ottoman Empire), and felt again it wasn't getting it's fair share of the spoils of war. Great Britain had inserted a little bit of competition in Asia, at Singapore, etc. So when WWII came, Japan was particulary ruthless.