The scary truth: Kim has again defied predictions

Joby Warrick analysis

The device that shook the mountains over the Punggye-ri test site on Sunday represented a quantum leap for North Korea’s nuclear capability, producing an explosion at least five times greater than the country’s previous tests and easily powerful enough to devastate a large city.

And if studies confirm that the bomb was a thermonuclear weapon — as North Korea claims — it would be a triumph of a different scale: a major technical milestone reached well ahead of predictions, putting the world’s most destructive force in the hands of the country’s 33-year-old autocrat.

The feat instantly erased lingering scepticism about Pyongyang’s technical capabilities and brought the prospect of nuclear-tipped North Korean intercontinental ballistic missiles a step closer to reality, US analysts and weapons experts said. Many predicted that a miniaturised version of the presumed thermonuclear bomb would soon be in North Korea’s grasp, and that it probably already exists.

“North Korea has achieved a capability to wipe out a big chunk of any major city,” said Sue Mi Terry, a former senior analyst on North Korea at the CIA and now managing director for Korea at the Bower Group Asia. “If the North didn’t test a hydrogen bomb, as they said they did this time around, they will get there very soon.”

The blast produced seismic waves equivalent to a 6.3-magnitude earthquake, or 10 times as strong as the country’s last nuclear test, which occurred a year ago this week. A conclusive analysis will take days or weeks, but weapons experts said the sheer force of the explosion is highly suggestive of a thermonuclear bomb. Sometimes called hydrogen bombs or H-bombs, these second-generation nuclear devices entered US and Soviet arsenals in the 1950s, threatening adversaries with a vastly greater destructive force compared with atomic bombs dropped on Japan in the final days of World War II.

Because of the H-bomb’s relatively complex two-stage design, many experts thought it would be months, or perhaps years, before North Korea’s scientists could master the necessary technology. When Pyongyang boasted last year that it had tested a thermonuclear device, many experts dismissed the claim as propaganda.

But on Sunday, the scepticism had mostly evaporated.

“There’s little doubt in my mind,” said James Acton, a physicist and co-director of the Nuclear Policy Programme at the Carnegie Endowment for International Peace, a Washington thinktank. “North Korea has been hinting for a while that it was working on an H-bomb — even apart from the photos it released last night — so this should not come as a huge surprise. But it does represent a significant technological advance.”

The apparently successful test came hours after leader Kim Jong Un appeared on state-run television with what appeared to be a prototype of a new North Korean thermonuclear bomb, in a remarkable display of his confidence in the capabilities of his country’s weapons engineers. Given North Korea’s other recent technical gains in producing long-range missiles and miniaturised warheads, US experts said there is little doubt about Pyongyang’s ability to eventually master all the steps needed to send a nuclear-tipped missile halfway around the world.

Although it is not known for certain that North Korea can build a miniaturised thermonuclear warhead that can fit on a missile, Acton said, “I believe we have to assume it can.”

The prototype displayed by Kim on the eve of the test “pretty well shows they know the essentials of a thermonuclear device design,” said Peter Zimmerman, a nuclear physicist and former chief scientist for the Senate Foreign Relations Committee.

Several other nuclear experts noted that the vaguely peanut-shaped metallic device shown on North Korean television bore features that were broadly consistent with a twostage hydrogen bomb, although it did not resemble any weapon in past or current US arsenals.