US and allies faced potential lengthy and costly campaign against japanese
Significance of island hopping and why US used it:
used air attacks and submarines to isolate japanese held areas - conquer the islands + use them to cut off ships supplying the well defended islands (cut off some areas from food, ammunition and essentials) - deprive J from key resources - further weaken them
Benefit of island hopping:
allowed allies to incur fewer casualties
allow them to come within striking distance of mainland J in a few years
(would take much longer to conquer every J stronghold rather than island hop)