North Korea claimed Sunday that it had developed a hydrogen bomb to use with a long-range intercontinental ballistic missile (ICBM).
The Korean Central News Agency, North Korea's propaganda arm, said that that dictator Kim Jong-un inspected "an H-bomb to be loaded into [a] new ICBM" during a visit to the North's Nuclear Weapons Institute. Photos accompanied the statement showed the purported hydrogen bomb being developed in a lab.
The explosive power of the "homemade" bomb is "adjustable from tens kiloton to hundreds kiloton," KCNA said.
Aside from the factuality of the North's claim, the language in its statement seems a strong signal that Pyongyang will soon conduct another nuclear weapon test, which is crucial if North Korean scientists are to fulfill the national goal of an arsenal of viable nuclear ICBMs that can reach the U.S. mainland. There's speculation that such a test could come on or around the Sept. 9 anniversary of North Korea's national founding, something it did last year.
There was no immediate comment from the Pentagon or other U.S. officials. However, Director of National Intelligence Dan Coats told Congress in March that North Korea had developed the ability to put a nuclear warhead on a missile.
Experts have previously expressed skepticism about previous North Korean weapons claims. However, the announcement will raise already high worries in East Asia and in Washington that the North is closer to its goal of an arsenal of viable nuclear ICBMs that can reach the U.S. mainland.
In July, conducted its first ever ICBM tests, part of a stunning jump in progress for the country's nuclear and missile program since Kim rose to power following his father's death in late 2011. The North followed its two tests of ICBMs, which, when perfected, could target large parts of the United States, by threatening to launch a salvo of its Hwasong-12 intermediate range missiles toward the U.S. Pacific island territory of Guam in August.
It flew a Hwasong-12 over northern Japan last week, the first such overflight by a missile capable of carrying nukes, in a launch Kim described as a "meaningful prelude" to containing Guam, the home of major U.S. military facilities, and more ballistic missile tests targeting the Pacific.
North Korea has conducted five nuclear tests since 2006, including two last year. The first of those tests involved what it claims to have been a hydrogen bomb and the second was its most powerful ever.
The key question is how far North Korea has gotten in efforts to consistently shrink down nuclear warheads so they can fit on long-range missiles.
South Korea's main spy agency has previously asserted that it does not think Pyongyang currently has the ability to develop miniaturized nuclear weapons that can be mounted on ballistic missiles. Some experts think the North may have mastered this technology.
North Korea is thought to have a handful of rudimentary nuclear bombs and has spent decades trying to perfect a multistage, long-range missile to eventually carry smaller versions of those bombs.
Fox News' Lucas Tomlinson and The Associated Press contributed to this report.