North Korea continues tunnelling work at nuke test site despite aftershocks, watchdog says

North Korea continues to tunnel at the secretive state’s mountainous nuclear test site despite several aftershocks at the site that were likely caused by the country’s massive nuclear test in September, according to a U.S.-based watchdog.

In its latest analysis of satellite imagery, 38 North reported tunnel work is still being conducted at the Punggye-ri test site.

Kim Jong Un and his regime conducted the North’s sixth nuclear test on Sept. 3 from an area the watchdog dubbed the “North Portal” of the mountain, and work at a “West Portal” has been underway for quite some time.

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“These efforts continue to be concentrated at the West Portal, leaving the North Portal — where the last five tests were conducted — mostly dormant and likely abandoned, at least for the time being,” the watchdog noted Monday. “At the West Portal, there has been a consistently high level of activity since North Korea’s last nuclear test.”

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The watchdog had previously noted work at the West Portal in early November, reporting movement of equipment and materials “providing sufficient evidence that mining personnel have been inside the West Portal.”

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Since Kim’s latest nuclear test, the mountainous area has experienced several small tremors, with the most recent on Saturday, which is a likely result of the September test, according to the U.S. Geological Survey.

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READ MORE: North Korea earthquake a sign of instability at nuclear test site, say experts

The aftershocks, of magnitude 2.9 and 2.4, were detected at 1:13 a.m. and 1:40 a.m. EST respectively, said the USGS and Lassina Zerbo, executive secretary of the Vienna-based Comprehensive Nuclear-Test-Ban Treaty Organization.

A tweet from Zerbo said analysts had confirmed that the activity was “tectonic” in origin.

“They’re probably relaxation events from the sixth nuclear test,” the official said. “When you have a large nuclear test, it moves the earth’s crust around the area, and it takes a while for it to fully subside. We’ve had a few of them since the sixth nuclear test.”

South Korea’s National Intelligence Service (NIS) suggested to lawmakers on Nov. 2, a tunnel at North Korea’s mountainous nuclear site was primed for another test “at any time” but also noted the possibility of damage at the Punggye-ri test site.

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The North conducted its first missile test on Nov. 28 after a 70-day lull in activity. The North’s latest launch came after South Korea warned Kim’s regime could have its nuclear arsenal completed sooner than expected.

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“Experts think North Korea will take two to three more years but they are developing their nuclear capabilities faster than expected,” South Korean Unification Minister Cho Myoung-gyon warned last month. “We cannot rule out the possibility that Pyongyang may declare the completion of their nuclear program in a year.”

According to 38 North, the recent activity suggests the North is expanding its nuclear operations.

“These activities suggest that tunnel excavation is underway at the West Portal, as the North Koreans expand the site’s potential for future nuclear testing,” the watchdog noted.

— with a file from Reuters