Question

Which island was concidered a stepping stone for an invasion of the Japanese mainland

Answer 1

Iwo Jima - although not strictly a stepping stone it gave the US an airbase that was reasonably far forward and at the same time deprived the Japanese of an airbase allowing bombing raids on mainland Japan to proceed with less interference.

Step-by-step explanation:

Answer 2

Iwo Jima was the island considered as a stepping stone to the jap mainland.