North Korea has dug a new 800 m-deep tunnel at its nuclear test site in Punggye-ri, North Hamgyong Province, it emerged on Sunday. Experts believe it will be ready for another nuclear test once it reaches a depth of 1 km.
A South Korean government source said, "If they continue digging the tunnel in Punggye-ri at the current speed, they could likely conduct a third nuclear test anytime after early April."
The tunnel had reached a depth of about 500 m by December. South Korean and U.S. intelligence agencies estimate progress based on satellite images of mounds of soil dug from the tunnel.
◆ Nuclear Tests
The North conducted two nuclear weapons tests in 2006 and 2009, but the first bomb had a yield of just 0.8 kt (1 kt equals 1,000 tons of TNT), and the second 4-5 kt. The yield of the Hisroshima bomb in 1945 was 15 kt.
"India and Pakistan became nuclear weapons states after five and six nuclear tests," said Cheon Seong-whun, a senior research fellow at the Korea Institute for National Unification. "The North is also going to need further tests."
The first two bombs used plutonium, but there is speculation that the next one could be uranium-based, according to a South Korean military source. The North is believed to have 30-50 kg of weapons-grade plutonium, and another test would deplete these reserves now a plutonium-producing reactor at Yongbyon has been switched off.
But the North stunned neighboring countries last November by showing an "ultra-modern" uranium enrichment facility to a visiting U.S. nuclear expert.
The North could also be weighing other provocations. It recently completed a new ballistic missile test site in Tongchang-ri, North Pyongan Province and could test a long-range missile there once radar has been installed, experts say.
A base for about 70 hovercraft is reaching completion at Koampo, South Hwanghae Province, 50 to 60 km from Baeknyeong Island in the West Sea. Each hovercraft is capable of carrying 30 to 50 commandos to the South Korean island at 70-90 km/h.
The South Korean military believes that North Korean commandos could make surprise landing on Baeknyeong Island from the new hovercraft base in just 30-40 minutes.
Baek Seung-joo, the director of the Center for Security and Strategy at the Korea Institute for Defense Analyses, said, "The North has always been able to get what it wants through a mixture of dialogue and provocations, so now it's trying to show that it could carry out provocations anytime unless South Korea and the U.S. yield to its demands for dialogue."
A North Korea source said it is equally likely that the North will try to help leader Kim Jong-il's son and heir Jong-un establish a record of achievements by testing a nuclear weapon, which is seen as a symbol of its "military-first" doctrine.