STORY HIGHLIGHTS
- North Korea has warned that it plans to carry out underground nuclear tests
- Would be the third nuclear test Pyongyang has carried out since 2006
- Comes after new U.N. sanctions for North Korea's December satellite launch
- Experts say its unknown how close the North is to being able to launch a nuclear warhead
(CNN) -- North Korea's intention to carry out a new nuclear test, coming on the heels of December's successful satellite launch, suggests that Pyongyang is moving forward toward developing a nuclear warhead and a deliverable missile system, experts say. The question remains: How close are they?
The answer, like the cloistered "hermit kingdom," remains largely a mystery as does much of its nuclear program.
"It's a question over the delivery system and the reliability of those systems," said Daniel Pinkston, senior analyst for the International Crisis Group covering Northeast Asia. "That is essentially unknown, or known by a few people inside North Korea."
South Korean rocket successfully puts satellite in orbit
A 2009 report by International Crisis Group suspects that North Korea "probably has somewhere between six and twelve nuclear weapons, or at least explosive devices," but notes that experts are divided whether any of these to be now useable as warheads -- small enough to be mounted on missiles and durable enough to withstand the hazards of flight.
"It's pretty clear that these are advanced technologies and the systems present a number of engineering challenges -- and to master these technologies requires a number of tests," Pinkston said.
North Korea on Google Maps: Monuments, nuclear complex, gulags
Last month, on the first anniversary of Kim Jong Il's death, North Korea successfully launched a three-stage rocket that put the satellite, Shining Star-3, into orbit. The launch also signaled that the North's long-range missile program now puts the United States within reach.
Last week, the United Nations Security Council unanimously passed a resolution that strengthened sanctions against the north in response to the December rocket launch. Declaring sanctions to be tantamount to "a declaration of war," North Korea is threatening further missile and nuclear tests which it said are a new phase of confrontation with the United States.
For the U.N. and North Korea: Game on
A new underground nuclear test would be the third, following tests in 2009 and 2006. While seismographs will be able to confirm if North Korea has an underground test, the size of the nuclear blast will be difficult to determine, Pinkston said.
"From what I understand it is virtually impossible to mask a nuclear event in terms of concealing it due to seismographs," Pinkston said. "But as far as the accuracy of the assessment of the yield, that's where the difficulty lies."
Koreas in 2013: Watch the generational politics
Estimates of the size, or "yield," of the 2009 nuclear test range from 2.5 kilotons to 6 kilotons, Pinkston said. By comparison, the atomic bomb dropped on Hiroshima had a yield of 16 kilotons.
While the specter of a North Korea able to send nuclear-tipped missiles is worrisome, equally troublesome to the international community is Pyongyang's atomic technology fuelling the black market for weapons.
"If its clandestine uranium-enrichment program has made strides, Pyongyang could demonstrate that it will gain access to a far larger pool of fissile material than simply its limited supply of weapons-grade plutonium," wrote Patrick M. Cronin, an Asian expert at the Center for New American Security, in a CNN op-ed. "A larger pool of fissile material is a dual threat: As a vital part of an expanded nuclear weapon program and as a commodity to be sold on the black market."
Timeline: North Korea's rocket-fueled obsession
