美国国家公共电台 NPR--North Korea is being monitored for its first test of a nuclear weapon in 5 years（在线收听）

North Korea is being monitored for its first test of a nuclear weapon in 5 years

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North Korea this year scrapped a five-year moratorium on testing ballistic missiles. So far, it has not resumed testing nuclear bombs. But it is believed to be about to do that very soon.

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Right after North Korea admitted its first COVID-19 outbreak, after denying for two years that it had a single case, it tested three ballistic missiles. Last week, it made this its 16th test launch of the year. Now as NPR's Anthony Kuhn reports, the U.S. and South Korea are watching for another kind of test, the first involving a nuclear weapon in five years.

ANTHONY KUHN, BYLINE: Deep in the mountains of North Korea, about 60 miles from the border with China, there's a village called Punggye-ri. And near that village is North Korea's main nuclear test site.

JEFFREY LEWIS: Imagine that you're next to a creek and all around you are these very tall mountains.

KUHN: Jeffrey Lewis is an arms control expert at the Middlebury Institute of International Studies in Monterey, Calif.

LEWIS: To your north, there is a tunnel entrance. And inside that mountain, there is a network of tunnels where North Korea did five of its last six nuclear tests.

KUHN: The other test was done in the same complex, but in a different tunnel. North Korea partially dismantled Punggye-ri in 2018. It declared a moratorium on nuclear testing and began a yearlong period of summit diplomacy. This March, Lewis looked at satellite pictures and saw signs of construction, suggesting that North Korea could be planning to resume nuclear testing. One danger of underground nuclear tests is that radiation could leak out. But Lewis believes Punggye-ri is pretty solid.

LEWIS: There are several hundred meters of granite above those test tunnels, which is more than enough to contain even very large nuclear explosions.

KUHN: There are, of course, riskier ways of testing atomic bombs than detonating them underground. Adam Mount, a fellow at the Federation of American Scientists, explains.

ADAM MOUNT: The major risk is that they mount a nuclear warhead on a ballistic missile, fire it over Japan into the Pacific and detonate it above the surface of the water.

KUHN: This year, North Korea has tested many kinds of missiles - long-range, short-range, submarine-launched, train-launched, hypersonic and cruise missiles. Mount says all of these may carry nuclear warheads which first need to be tested.

MOUNT: Depending which systems they want to make nuclear-capable, it may require them to develop a generation of new nuclear warheads for those systems.

KUHN: North Korea needs to miniaturize the warheads. And to make its nuclear deterrent credible, Mount says, they need to prove the weapons really work.

MOUNT: Until Kim Jong Un is sure that the United States believes that he has a functional nuclear deterrent, he may have an incentive to continue to demonstrate that he does. Kim Jong Un has a very strong incentive to convince the U.S. President personally.

KUHN: President Biden will meet with South Korean President Yoon Seok-youl this Sunday in Seoul, and experts think that a nuke test this month is highly likely. This test would signal the end of a five-year-long testing moratorium. By scrapping the moratorium, Jeffrey Lewis says, Pyongyang will be clearing away a major obstacle to its nuclear ambitions.

LEWIS: When Kim Jong Un agreed to stop testing long-range missiles and when he agreed to stop exploding nuclear weapons, that was a real constraint not on his deterrent that he had at that time, but on his ability to build the deterrent that he is about to embark on.

KUHN: With nuclear talks between the U.S. and North Korea stalled since 2019, the prospect of negotiating a new moratorium appears for now to be nowhere on the horizon.

Anthony Kuhn, NPR News, Seoul.

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