A U.S.-based website dedicated to taking apart satellite images taken above the reclusive North Korea assessed that Pyongyang continues to restore a shaft at a nuclear testing facility it claimed to have demolished in 2018.

Citing satellite imagery on Thursday, 38 North said a gray-tone spoil pile across from a new tunnel entrance at the Punggye-ri nuclear testing facility continues to expand, indicating ongoing excavation.

Its southeast of the tunnel entrance has been cleared of trees, but the website said the purpose remains unclear.

Two new support buildings were built between April 6 and 14 in the southern support area for a total of four structures since January. This new construction parallels ongoing roof repair work at some of the older support buildings, although the refurbishment is happening at a slower pace.

Despite such speculation, 38 North said there were no signs of the regime gearing up for a nuclear test, such as increased vehicle activity or the arrival of test support equipment and instrumentation.

Referring to work on support infrastructure, the website suggested it may be a part of Pyongyang's long-term plans for site operations.