What different challenges did the United States face fighting in the Pacific versus fighting in Europe?
Probably the greatest challenge was distance. The Pacific Ocean presented a much larger area over which fighting could occur. In addition, land from which forces could be staged and on which supplies could be collected and distributed was only available in the form of small and isolated islands. As a result, the logistics of conducting the war against Japan were much more complicated than those of the war in Europe.
Forces and armaments had to be transported by ship to islands that were recaptured from Japan, often at tremendous cost of lives and equipment. Airplanes were used for protection of troops and for bombing of Japanese ships, but were limited by the range they could fly before they had to return to aircraft carriers for more fuel.