North Korea threatened specific bases in Japan and Guam

The difference being that Japan had a powerful and competent Navy. The U.S. just had better infrastructure/economy to keep our military strong while Japan had difficulty sustaining its fighting capability through losses. North Korea's fighting capability is almost purely ground-war and anti-air.

What? Japan lost because we placed an embargo on them which crippled them and made them go for a shot in the dark to try to demoralize us so we wouldn't participate