SEOUL, South Korea (AP) — North Korean leader Kim Jong Un inspected the loading of a hydrogen bomb into a new intercontinental ballistic missile, Pyongyang's state media said Sunday, a claim to technological mastery that some outside experts will doubt but that will raise already high worries on the Korean Peninsula.

As part of North Korea's work to build an arsenal of viable nuclear ICBMs that can reach the U.S. mainland, Kim inspected during a visit to the North's Nuclear Weapons Institute the loading of a "homemade" H-bomb into an ICBM.

The explosive power of the bomb is adjustable from ten...