Signs suggest North Korea is preparing for nuclear test

SEOUL • North Korea looks set to detonate its first nuclear bomb in more than four years, as America's sanction disputes with Russia and China make further United Nations penalties against Pyongyang unlikely.

Workers have been observed digging a new passageway at the Punggye-ri site where North Korea conducted all six of its previous nuclear tests, South Korean media - including the DongA Ilbo newspaper - reported.

A test could come as soon as next month, when Mr Kim Jong Un is preparing to mark the 110th anniversary of the birth of his grandfather, state founder Kim Il Sung, the paper said, citing a security official it did not identify.

The reports came as Mr Kim delivered a fresh warning to the United States that he planned to develop more "powerful striking capabilities", the official Korean Central News Agency reported on Monday.

The weapons would make North Korea more secure and "control all threats and blackmail by the imperialists", it reported him as saying.

While Mr Kim has been signalling plans to resume major weapons tests for more than two years, the US campaign to punish Russia over its invasion of Ukraine has reduced the risk of getting sanctions for such provocations.

Any additional measures from the UN Security Council would require support from Russia, as well as China, which has led the criticism of Washington's efforts to squeeze Moscow economically.

Their reluctance was clear during a Security Council meeting last Friday to discuss North Korea's first launch of an intercontinental ballistic missile (ICBM) since November 2017. Russia's representative, Ms Anna Evstigneeva, rejected US calls for what she described as "turning the sanctions screw" against North Korea and advocated for a resolution drafted with China that would prioritise negotiations.

"North Korea almost certainly views the rifts between the US and Russia, and the US and China, as a golden opportunity to conduct longer-range missile - and probably even nuclear - tests," said non-resident fellow Rachel Minyoung Lee of the 38 North Programme at the Stimson Centre.

The response to the ICBM test shows how much the geopolitical landscape has shifted since 2017, when then-US President Donald Trump threatened to unleash "fire and fury" against North Korea and secured China and Russia's support for tough UN sanctions against the regime.

Mr Trump subsequently launched a trade war against China and opened direct talks with Mr Kim, prompting President Xi Jinping in Beijing to repair ties with Pyongyang as well.

Although North Korea still languishes under a range of UN sanctions, it has continued to roll out an array of new missiles that would require smaller, more advanced warheads to pose a credible deterrent to the US. Such weapons could increase Mr Kim's leverage if he decides to return to nuclear disarmament talks and ease the sanctions choking the economy.

In the closing days of Mr Trump's term, Mr Kim laid out a five-year road map for his nuclear programme that included making warheads smaller and lighter, as well as more powerful.

Weapons mentioned in that speech, such as hypersonic missiles that are designed to evade US-operated missile shields and hit American bases in South Korea and Japan, have been among those tested in recent months.

The recent work at the Punggye-ri site appears designed to reverse Mr Kim's efforts to dismantle the site before his first landmark summit with Mr Trump in June 2018.

That demolition was intended to demonstrate North Korea's commitment to a self-imposed testing freeze that Mr Kim later declared null and void after talks with Mr Trump fell apart.

Observers will be watching where in the site's various tunnels any bomb is detonated for clues about Mr Kim's aims, said senior research fellow Lee Choon-geun at South Korea's Science and Technology Policy Institute.

South Korea's military has detected signs of work at tunnel No 3, the DongA newspaper said.

"If North Korea conducts its next nuclear test in the third tunnel, then it is testing its nuclear warhead miniaturisation technology for tactical nuclear weapons," Mr Lee said.

A fourth tunnel was believed to be reserved for testing thermonuclear devices, he said.

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