North Korea has dug a new tunnel more than 500 m deep at a nuclear test site in Punggye-ri, North Hamgyong Province, intelligence sources said Tuesday. The North is also reportedly accelerating massive excavation work and construction of a new building at its main nuclear site in Yongbyon.
"North Korea seems to be busy digging even in winter when the ground is frozen" at Punggye-ri and Yongbyon, a South Korean intelligence officer said.
Based on an estimate of the amount of earth dug up, the intelligence officer speculated that the North has already dug a cave more than 500 m deep in Punggye-ri.
"If progress goes on at the current pace, the North will have dug a cave 1 km deep, the depth where it is possible to conduct a nuclear test, between March and May next year," the officer said.
Voice of America, quoting a U.S. Congressional Research Service report, reported on Dec. 7 that the North could conduct a nuclear test as a proxy for nuclear weapons developing nations such as Iran.
The North is also carrying out massive construction in Yongbyon. Experts including Siegfried Hecker, a U.S. nuclear scientist who visited Yongbyon last month, believe that the North is building a 25-30 MW reactor.
But a South Korean security official said, "The North has never admitted what it is building. We're just speculating that it's building a nuclear facility whose purpose is unclear."
South Korean government officials believe the North does not have enough technical wherewithal to build a light-water reactor power plant that uses enriched uranium as fuel and suspect it is now openly attempting to build a highly-enriched uranium facility to produce nuclear weapons. They also suspect that the North has three or four more undisclosed uranium enrichment facilities in addition to the one in Yongbyon it showed Hecker last month.
South Korea and the U.S. are worried that the North could heighten tensions on the peninsula by using a nuclear threat after the artillery attack on Yeonpyeong Island. It apparently aims to sway public opinion in the international community and South Korea in favor of early talks with the North by either conducting a third nuclear test or boosting its uranium-based nuclear capability.
Former chief U.S. nuclear negotiator Christopher Hill was quoted by VOA as saying that the North's disclosure of the uranium enrichment plant proves that the regime lied in the six-party talks.