Analysis: N. Korea still unable to mount nuclear attack

North Korea may have the bomb. But the twin complexities of developing nuclear warheads from a successful test explosion and the ways of delivering them means the country may be years away from posing an atomic threat to the rest of the world.

The mere fact that the North has apparently managed to set off an underground nuclear blast is alarming enough because it not only moves the volatile communist nation a giant step closer to having atomic arms but also demonstrates its determination not to be swayed by worldwide pressure to step back from the brink. In testing its device, North Korea would even be ignoring China, its closest ally, most important economic partner and the North's guarantor of oil.

"It's all a bit jaw-dropping, in terms of how swiftly the test has been conducted," said Alex Neill, head of the Asian security program at the Royal United Services Institute, a British defense think tank. He said expectations had been that there would be a six- to 12-month hiatus between the regime's October 3 announcement of its intended test and the actual blast Monday.

Still, a test is just that - an experiment that needs years of development before it turns into the finished product. In this case, that product would be nuclear weapons that could menace - and hit - not only the North's neighbors but enemies like the US thousands of kilometers (miles) away.

Bomb weaker than one used in Hiroshima

The secretive North is an enigma as far as its military capabilities are concerned. And its nuclear development also remains shrouded in mystery since it kicked out inspectors of the International Atomic Energy Agency and then withdrew from the Nuclear Nonproliferation Treaty in early 1993.

Still, both its nuclear and missile technology are believed to be lacking the sophistication needed to develop warheads and the ways to deliver them.

The power of the blast appears to back that assumption.

Ahead of Monday's reported explosion, former UN nuclear inspector David Albright, president of the Washington-based Institute for Science and International Security, speculated that the test bomb would have a yield three to four times weaker than the bombs that destroyed the Japanese cities of Hiroshima and Nagasaki during World War II because of the North Koreans' lack of ability to produce a stronger weapon.

Indirectly confirming Albright's comments on Monday, both Russian and South Korean officials said seismic measurements showed the blast was far weaker than those dropped on the two Japanese cities.

'Can't put bomb on missile'

Size matters as well. Rudimentary test bombs can be the size of small trucks, ruling them out as missile payloads. While smaller, even the bomb dropped from aircraft on Nagasaki weighed nearly 6 tons.

"They can deliver it, put it on a cargo ship, drop it from a cargo plane," said Gordon Chang, author of "Nuclear Showdown: North Korea Takes On the World." "The point is, can they shrink it to put it on a missile? I don't think they can."

David Wall of London's Chatham House strategic think tank said the likelihood of Pyongyang possessing a nuclear weapon that can be delivered by a missile "is zero."

"He could put it in the back of a taxi and drive it to Seoul," Wall said of Kim Jong Il, the North's leader. There are suspicions that Pakistan may have provided North Korea with nuclear weapon design information in exchange for help in developing missile expertise in the 1990s. But even if it had the technology to shrink its bomb to payload size, any Northern nuclear arsenal would pack a limited punch.

Estimate: Nuclear strike capability within next decade

The amount of plutonium or enriched uranium at the North's disposal for the fissile core of warheads is unknown. But estimates put it as enough for no more than 13 weapons, compared to the thousands of warheads the United States has at its disposal.

And Pyongyang's ability to deliver such warheads is also in doubt.

The communist nation shocked the world in 1998 by firing a long-range ballistic missile over Japan into the Pacific Ocean. And it successfully test-launched seven missiles in July.

But a long-range rocket believed capable of reaching US shores exploded shortly after takeoff.

"They don't yet have nuclear devices that can be delivered and their carriers are at the development stage," said Pavel Zolotarev, an arms expert with the US and Canada Institute in Moscow.

Still, there is general agreement that unless the North scraps its nuclear program or is forcibly stripped of it, Pyongyang will be able to launch a nuclear strike within the next decade.

With North Korean missiles already putting the country's neighbors within reach, "it's only a matter of time and effort" until Pyongyang develops both the long-range means to strike at America and the nuclear payload to arm such weapons, said Anatoly Dyakov, head of the Moscow-based Center for Arms Control.