U.S. and allied officials challenged North Korea’s claim of thermonuclear success, but voiced concern Wednesday that the secluded nation is gradually mastering the technology of miniaturizing nuclear warheads, allowing them to be launched on trans-Pacific missiles.
Pyongyang’s announcement that it had detonated a hydrogen bomb, although dubious, also spurred concern about the proliferation of weapons of mass destruction in Asia and the Middle East.
By advancing its warhead technology while refining its missiles, Pyongyang could eventually threaten the U.S. mainland and American allies South Korea and Japan. Pentagon officials had said last year that North Korea likely had the capability to miniaturize a nuclear weapon.
Read the full article in the Wall Street Journal.