Columbia University Contemporary World Discussion

I’m working on a history question and need an explanation and answer to help me learn.

We discussed how the United States truly became a burgeoning empire when it won the Spanish-American War, and it became the heir of vast territories of the Spanish Empire. The Philippines was one of these regions, and along with many other areas and islands throughout the Asia-Pacific region U.S. influence exploded in the early 20th century. What was happening in the region preceding WW2, how did Japan see things, and what was the status of the US ally in China/Manchuria? Why did Japan attack the UK and US bases/territories in 1941?