What problems did Japan face in building an empire in the Pacific?

The problems faced by Japan when building an empire in the pacific includes;

- Japan needed oil for its empire building, and US cut off oil exports to Japan.

-US naval resistance proved stronger than expected

- US sent aid to the Chinese who were trying to resist Japanese invaders.

- The Empire got big fast, and did not treat conquered people well.

The main problem that Japan faced in building an empire in the Pacific is that they had very few natural resources of their own, due to the small nature of their island nation--meaning that they had to often invade territories such as China to gain such materials.