SEOUL, June 26 (Yonhap) -- North Korea has started new tunneling work at its nuclear test site, a U.S. think tank said Wednesday, citing recent satellite imagery.
According to "38 North," an analysis program of the U.S.-Korea Institute at Johns Hopkins University in Maryland, work is being carried out at the west portal area of the Punggye-ri test site in the remote northeastern part of the communist country.
Punggye-ri was used by Pyongyang as the site of all three of its nuclear tests, with the latest taking place on Feb. 12.
38 North said the activities probably started in late April and gathered momentum in the following weeks.
The exact purpose of the work cannot be determined at present, but the U.S. think tank speculates it may be a move to construct another tunnel, or part of an effort to repair and clear debris from existing tunnel systems that may have been damaged by past nuclear tests, it said.
"These activities do not appear to be part of preparation for a nuclear test in the near-term. Rather, they seem to be long-term projects," the think tank said. It pointed out that digging a fresh tunnel for use in a nuclear test can take years.
Echoing this view, an official at Seoul's unification ministry, who did not wish to be identified, said activities at the nuclear test site are nothing new.
"There has always been some movement at the site and all information gathered by Seoul show no signs that something imminent is about to happen," he said.
The official pointed out that Punggye-ri is under close observation and that besides actual work at the site, the government is keeping tabs on various other signs that could indicate a major development taking place.
South Korea's defense ministry also confirmed earlier in the day that it was aware of activities on the west portal, yet made clear there are no real signs that the North is preparing to conduct another nuclear test.
The isolationist country, meanwhile, has been slapped with sanctions after its nuclear test in February, with the international community warning Pyongyang not to take actions that could further escalate tensions.
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