Washington believes that North Korea has a large stockpile of chemical and biological agents as well as nuclear bombs.

In addition, North Korea has an advanced missile programme and the world's fifth largest armed forces made up of more than one million troops.

The conventional threat posed by Pyongyang is significant enough, even if consensus is lacking on whether or not North Korea's drive to acquire the atomic bomb has been successful.

In the past North Korea has threatened to turn Seoul into a "sea of fire" using conventional firepower -- artillery and rocket batteries embedded along the border.

Most experts are keeping an open mind on North Korea's nuclear programme because the country is so tightly controlled and they have too little information to work on.

More is known about Pyongyang's quest for chemical and biological weapons that dates back to the 1950s. Reports emerged last year that political prisoners had been used as guinea pigs to test chemical warfare agents.

Washington says North Korea is running a plutonium-producing nuclear programme at its Yongbyon complex 90 kilometers (50 miles) north of Pyongyang and a separate uranium-based programme at unknown locations.

Siegfried Hecker, a US atomic expert who visited the controversial Yongbyon nuclear research complex in January last year, said he was far from certain North Korea was able to build a plutonium-based nuclear bomb.

"I saw nothing and spoke to no one who could convince me that they could build a nuclear device with (plutonium), and that they could weaponize such a device into a delivery vehicle," he said in public testimony after his return.

Washington believes North Korea diverted enough plutonium prior to its 1994 nuclear freeze accord with the United States to make about two bombs.

Pyongyang could be in the process of adding half-a-dozen more after reprocessing some 8,000 spend fuel rods it unloaded from the reactor in 2003.

North Korea claimed last month that it unloaded another 8,000 spent fuel rods after shutting the reactor down earlier this year. If it reprocesses those rods, North Korea could have a total of around 11 nuclear bombs sometime next year.

South Korea prefers to remain sceptical about North Korea's claims.

However, the Bush administration is working on the assumption that it is more prudent to factor in the worst-case scenario.

And that would incline the administration to the view that not only has the regime developed nuclear weapons, but it has mastered the technology to deliver them by missile.

Throughout the 1980s and 1990s, North Korea carried out more the 100 tests of high-explosive triggers that would help them in their efforts to miniaturize nuclear warheads.

Pyongyang's vice foreign minister Kim Gye-Gwan told the US television network ABC in a Pyongyang interview broadcast on Wednesday that North Korean scientists lacked no technological skills.

"I want you to know that our scientists have the knowledge, comparable to other scientists around the world," he said. "You can take it as you like."

North Korea's medium-range Rodong missile can travel up to 1,300 kilometers, meaning it is capable of hitting targets in most areas of Japan.

Pyongyang in 1998 test-fired a Taepodong-1 missile with a range of up to 2,500 kilometers that overflew Japan and is said to be developing the Taepodong-2 with a range of 6,700 kilometers, bringing parts of the continental United States within reach.

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