The entrance to a tunnel at the Punggye-ri nuclear test site. (Joint Press Corps)

Speculation continues to emerge about the possibility of a nuclear test taking place in North Korea in the near future. According to a high-ranking Daily NK source in the country, preparations for a nuclear test are in their final stages but are not yet finished.  

The source told Daily NK on Thursday that cables have been installed at the test site, and a temporary command has arrived at the Punggye-ri nuclear test site in Kilju, North Hamgyong Province, to inspect the preparations. All preparations for a nuclear test are moving toward completion, he added. 

The source explained that detonation devices have been installed in Tunnel No. 3 at the nuclear test site and work has been completed on the communication lines to record blast data. This means that a nuclear test can be carried out quickly as soon as the order is given.

However, Daily NK has yet to confirm whether the tunnel was backfilled with concrete or wood after the cables were installed. If the authorities have completed the backfilling, North Korea will very likely carry out its seventh nuclear test sometime this month.

Choongeun Lee, an honorary research fellow at South Korea’s Science and Technology Policy Institute (STEPI), told Daily NK by phone that after sealing the cave, radioactive substances like xenon can be found because the area is made of granite. He said that the detonation devices cannot be abandoned for long because they are sensitive to temperature and moisture, and that if North Korea completed the backfilling after installing the cables, a nuclear test could be imminent.

Within North Korea, however, there is talk that June is a more likely time for the test. Daily NK’s high-ranking source said the country could carry out a test whenever the Workers’ Party decides to do so, but it appears several more weeks will be needed for preparations. He said in the past, the temporary command was dispatched to the site only after preparations were all complete. This time, however, they were sent early.

The source explained that key researchers and cadres were sent earlier than initially planned because the final stage of preparations required a command-level inspection.

Yang Uk, an associate research fellow at the Asan Institute for Policy Studies, told Daily NK that the installation of the cables means that North Korea has completed the bare minimum of what is needed to carry out a nuclear test. However, he cautioned that this alone does not mean preparations are complete. Yang noted that prior to a test, the area around the nuclear test site needs to be “put in order,” but recent satellite imagery shows that there were still mounds of earth around Tunnel No. 3.

Yang further explained that considering all the warhead delivery methods North Korea has showed off so far, the country needs many kinds of nuclear warheads. As such, the authorities will likely take time to consider how big the warhead they want to test should be before making a final decision. 

When just considering tactical nuclear weapons, North Korea needs to manufacture smaller warheads weighing less than 300kg to put atop a KN-23 or KN-24, the so-called “North Korean Iskander.” Even smaller warheads of 200kg would be needed for so-called “new-type tactical guided weapons,” hypersonic missiles and cruise missiles. All of these warheads will likely require considerable time to develop. 

Some in North Korea are reportedly claiming that the country must carry out at least five nuclear tests before the completion of the state’s five-year plan to develop national defense. In fact, Daily NK’s source said the country is preparing for a range of tests, from small-yield tactical nukes to nuclear EMPs and thermonuclear weapons.

Most experts believe that if North Korea carries out a seventh test in Pungye-ri’s Tunnel No. 3, which is currently undergoing restoration, it will be a small-yield tactical nuke.

Lee, the honorary research fellow at STEPI, said North Korean authorities would have to carry out a thermonuclear test in Tunnel No. 4, and while they could carry out an EMP test in Tunnel No. 3, they would need to dig a “branch tunnel” about 100 meters deep. He noted that there has been no confirmation that they have done this, however. Lee further pointed out that while it is very likely the country will test a small-scale tactical nuke, the authorities are unlikely to stop at just a one-off test.

Translated by David Black. Edited by Robert Lauler. 

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Seulkee Jang is one of Daily NK's full-time journalists. Please direct any questions about her articles to