WASHINGTON -- North Korea is widely recognized as being years away from perfecting the technology to back up its threats of a pre-emptive strike on the U.S. But some nuclear experts say it might have the know-how to fire a nuclear-tipped missile at South Korea and Japan, which host U.S. military bases.
No one can tell how much technological progress North Korea has made, aside from a few people close to its leadership. And it is highly unlikely Pyongyang would launch such an attack, because the retaliation would be devastating.
The North's third nuclear test on Feb. 12, which prompted the toughest UN Security Council sanctions yet against Pyongyang, is presumed to have advanced its ability to miniaturize a nuclear device. And experts say it's easier to design a nuclear warhead that works on a shorter-range missile than one for an intercontinental missile.
The assessment of David Albright at the Institute for Science and International Security think-tank is that North Korea has the capability to mount a warhead on its Rodong missile, which has a range of 1,280 kilometres and could hit South Korea and most of Japan. But he cautioned in his analysis, published after the latest nuclear test, that it is an uncertain estimate.
Albright says the experience of Pakistan could serve as precedent. Pakistan bought the Rodong from North Korea after its first flight test in 1993, then adapted and produced it for its own use. Pakistan, which conducted its first nuclear test in 1998, is said to have taken less than 10 years to miniaturize a warhead before that test.
North Korea also obtained technology from the trafficking network of A.Q. Khan, a disgraced pioneer of Pakistan's nuclear program, acquiring centrifuges for enriching uranium. According to the Congressional Research Service, Khan may also have supplied a Chinese-origin nuclear weapon design he provided to Libya and Iran, which could have helped the North in developing a warhead for a ballistic missile.
But Siegfried Hecker of Stanford University, who has visited North Korea seven times and been granted unusual access to its nuclear facilities, is skeptical the North has advanced that far in miniaturization of a nuclear device.
"Nobody outside of a small elite in North Korea knows -- and even they don't know for sure," he wrote in an email. "I agree that we cannot rule it out for one of their shorter-range missiles, but we simply don't know."
"Thanks to A.Q. Khan, they almost certainly have designs for such a device that could fit on some of their short or medium-range missiles," said Hecker, who last visited the North in November 2010. "But it is a long way from having a design and having confidence that you can put a warhead on a missile and have it survive the thermal and mechanical stresses during launch and along its entire trajectory."
The differing opinions underscore a fundamental problem in assessing a country as isolated as North Korea, particularly its weapons programs: Solid proof is tough to come by.
For example, the international community remains in the dark about the latest underground nuclear test. Although it caused a magnitude 5.1 tremor, no gases escaped, and experts say there was no way to evaluate whether a plutonium or uranium device was detonated. That information would help reveal whether North Korea has managed to produce highly enriched uranium.
The guessing game about the North's nuclear-weapons program dates back decades. Albright says in the early 1990s, the CIA estimated North Korea had a first-generation design for a plutonium device that was likely to be deployed on the Nodong missile. "Given that 20 years has passed since the deployment of the Rodong, an assessment that North Korea successfully developed a warhead able to be delivered by that missile is reasonable," Albright wrote.
According to Nick Hansen, a retired intelligence expert, the Rodong missile was first flight-tested in 1993. Pakistan claims to have re-engineered the missile and successfully tested it, although doubts persist about its reliability.
Whether North Korea has also figured out how to wed the missile with a nuclear warhead has major ramifications not just for South Korea and Japan, but for the U.S. itself, which counts those nations as its principal allies in Asia and retains 80,000 troops in the two countries.
U.S. intelligence appears to have vacillated in its assessments of North Korea's capabilities.
In 2005, Lowell Jacoby, director of the Defence Intelligence Agency, told a Senate committee North Korea had the capability to arm a missile with a nuclear device.
Pentagon officials, however, later backtracked.
According to the Congressional Research Service, a report from the same intelligence agency to Congress in August 2007 said "North Korea has short and medium-range missiles that could be fitted with nuclear weapons, but we do not know whether it has in fact done so."
Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said Friday the U.S. does not know whether North Korea has weaponized its nuclear capability.
Still, Washington is taking North Korea's nuclear threats seriously.
In December, North Korea launched a long-range rocket that could potentially hit the continental U.S. outh Korean officials say North Korea has moved at least one missile with "considerable range" to its east coast.
This week, the U.S. said two of the navy's missile-defence ships were positioned closer to the Korean peninsula, and a land-based system is being deployed for the Pacific territory of Guam. The Pentagon last month announced longer-term plans to beef up its U.S.-based missile defences.
South Korea is separated from North Korea and its huge standing army by a heavily militarized zone, and the countries remain in an official state of war, as the Korean War ended in 1953 without a peace treaty. Even without nuclear arms, the North positions enough artillery within range of Seoul to devastate the capital before the U.S. and South Korea could fully respond.
Experts say the North could hit South Korea with chemical weapons, and might also be able to use a Scud missile to carry a nuclear warhead.
Daryl Kimball of the Arms Control Association acknowledges the North might be able to put a warhead on a Rodong missile, but he sees it as unlikely. He says the North's nuclear threats are less worthy of attention than the prospects of a miscalculation leading to a conventional war.
"North Korea understands that a serious attack on South Korea or other U.S. interests is going to be met with overwhelming force," he said. "It would be near suicidal for the regime."
-- The Associated Press