US, South Korea and Japan vow strong response over North Korea's claimed hydrogen bomb test

SEOUL, South Korea — The United States, South Korea and Japan agreed to launch a "united and strong" international response to North Korea's apparent fourth nuclear test, as experts scrambled Thursday to find more details about the detonation that drew worldwide skepticism and condemnation.

It may take weeks or longer to confirm or contradict the North's claim that it successfully tested a hydrogen bomb, which would mark a major and unanticipated advance for its still-limited nuclear arsenal. Even a test of a less sophisticated atomic bomb would push its scientists and engineers closer to their goal of building a warhead small enough to place on a missile that can reach the U.S. mainland.

http://www.startribune.com/n-korea-says-it-conducts-successful-powerful-h-bomb-test/364339831/