Question

How did the fighting in Iwo Jima and Okinawa affect the Allies' Pacific strategy?

Answer 1

By influencing President Truman's decision to drop the atomic bomb on Japan.

Answer 2

It meant that the Soviets began sending troops into the Pacific, and that the US would stop the island hopping strategy, instead using air assault on the mainland. It also was a small example what fighting would be like in Japan if the US went through with operation Downfall.