"It seems to me they have demonstrated a willingness to export anything," Rumsfeld told an international gathering here of security experts and government officials.

"And to the extent they have the capability they have indicated they have, reasonable people in the world would have to assume they would be willing to sell or use most of those capabilities."

Rumsfeld said Washington and other parties to the talks with North Korea were working hard to get Pyongyang to dismantle its nuclear weapons program, with a third-round of negotiations expected to be held in Beijing this month.

"Needless to say time works to the advantage of North Korea," he said. "Assuming their behavior is to continue their programs, the longer it takes the more dangerous presumably their capabilities would become."

In a question and answer session at the Asia Security Conference, Rumsfeld was asked about concerns that North Korea was capable of smuggling a radiological bomb or even a nuclear weapon into the United States.

He said the United States was "imperfectly" arranged to prevent such threats and that countries needed to work more closely on such problems.

"I would submit the likelihood of terrorist networks or terrorist states getting their hands on these increasingly powerful weapons and using them is growing every year," he said.

"Which is why the counter-proliferation initiative is so important, countries simply must cooperate together because there is simply no way a single country can effectively deal with the problem of proliferation."

Rumsfeld said about 50 countries had expressed support for the Proliferation Security Initiative, a US-sponsored effort to increase global maritime security to prevent smuggling of weapons of mass destruction.

In a speech and in his remarks, Rumsfeld noted that Pakistani nuclear weapons scientist A.Q. Kahn had developed a network to supply nuclear technology to "outlaw" countries such as North Korea and Iran that spanned from Europe to Southeast Asia.

Pakistani President Pervez Musharraf pardoned Kahn for selling the country's nuclear secrets. But Rumsfeld said he was confident Musharraf had stopped him, and that his network had been dismantled.

However, he said: "You never know what you don't know."

Rumsfeld admitted that the United States had done a poor job in attacking the sources of terrorism, and stemming the flow of young Muslim extremists trained to "work the seams, the shadows and the caves."

"I am certain we have not been successful," he said, adding "the world has a problem."

On Iraq, he said the United States was engaged in a test of wills and that if it failed, the alternative was civil war, or ethnic cleansing, a breakup of the country, or the emergence of another Saddam Hussein "junior version."

Rumsfeld was questioned about the withdrawal of US ground troops from South Korea for duty in Iraq, and whether the reduction in force levels should have been used as leverage to gain similar reductions in North Korean forces.

"I think that you'll find the North Koreans will not believe there's been a weakening of the deterrent," Rumsfeld responded.

"When one looks at the totality of the US and the Republic of Korea's capabilities and how they are arranged and will be arranged, there may be some moving parts from time to time but the deterrent will be strong, it will be healthy and it will continue to contribute to stability in that part of the world for the foreseeable future."

Rumsfeld left Singapore on Saturday afternoon after two days in Singapore, with Bangladesh the second and final stop on his Asian trip.

WAR.WIRE