This month’s rocket launch by reclusive North Korea shows it has likely developed the technology, long suspected in the West, to fire a warhead more than 10,000 kilometers (6,200 miles), South Korean officials said on Sunday, putting the U.S. West Coast in range. North Korea said the December 12 launch put a weather satellite in orbit, but critics say it was aimed at nurturing the kind of technology needed to mount a nuclear warhead on a long-range missile. North Korea is banned from testing missile or nuclear technology under U.N. sanctions imposed after its 2006 and 2009 nuclear weapons tests,...