A US monitoring center claims that North Korea has begun digging a new tunnel for nuclear testing in the country’s east coast.
Satellite images from October and early November showed significant constructions at the Punggye-ri test site since April, the 38 North website run by Johns Hopkins University said in a report.
The site is where three previous nuclear tests were conducted but the new report said there are no signs a testing is imminent.
"While there are no indications that a nuclear test is imminent, the new tunnel adds to North Korea's ability to conduct additional detonations at Punggye-ri over the coming years if it chooses to do so," the report said.
The report comes almost a month after South Korea pointed to active movements of workers and vehicles at the site.
Pyongyang has vowed to continue nuclear tests and launch a rocket to put a satellite into orbit. The tests, North Korea says, are aimed at boosting defense capabilities in the face of enemy threats.
North Korea’s Atomic Energy Institute has said the country was fully ready to cope with US hostility with “nuclear weapons any time.”
Pyongyang is under UN sanctions over nuclear tests and for launching ballistic missiles considered by the West as being aimed at delivering nuclear warheads.
This is while the two Koreas are locked in a military stalemate since the end of their 1950-1953 war. No peace deal has been signed since then, meaning the two countries remain technically at war.