Asked if North Korea might be seeking to exploit U.S. attention on Iraq to re-start its nuclear weapons program, Rumsfeld said, "If they do, it would be a mistake."
He said the United States was able to wage two regional conflicts at the same time.
"We are capable of winning decisively in one and swiftly defeating in the case of the other," he said at a Pentagon briefing. "Let there be no doubt about it."
North Korea confirmed on Sunday it had begun removing U.N. seals and cameras at the Yongbyon nuclear reactor, which was idled in a watershed deal with the United States eight years ago. It said it did so to generate electricity.
U.S. Secretary of State Colin Powell on Monday consulted France, Russia and Britain about the situation and said the United States wanted a peaceful resolution, said State Department spokesman Philip Reeker. Over the weekend, Powell discussed the issue with Chinese, South Korean, Russian and Japanese officials among others.
The International Atomic Energy Agency said on Saturday that North Korea had disabled surveillance devices the agency had placed at the Yongbyon reactor. North Korea's official Korean Central News Agency later said seals and monitoring cameras were being removed "from the frozen nuclear facilities for their normal operation to produce electricity."
The IAEA also said North Korea had broken seals on about 8,000 spent fuel rods at Yongbyon which Washington and its allies fear could be used to produce plutonium for weapons. The CIA has previously estimated North Korea had enough plutonium produced before 1992 to make one or two nuclear weapons.
"Everybody is supportive of the IAEA view that North Korea's actions raise serious concerns and certainly belies their announced justification to produce electricity," Reeker said. "Spent fuel rods can be (used) to produce plutonium but they have no relevance to electricity generation."
"They are violating their responsibilities ... and we're not going to respond to threats or broken commitments," Reeker added. "We do want a peaceful resolution."
Unlike its stance on Iraq, which Washington has threatened with war if it fails to give up its suspected weapons of mass destruction programs, the United States has said it wants a peaceful resolution with North Korea since Pyongyang told U.S. officials in October it had a secret nuclear weapons program.
An INTERNATIONAL strike team composed of countries that could be targets of this in the region, led by the USAF, need to go in and neutralize this before it goes any further. No 10-month U.N. studies on the matter and games of cat and mouse. We know precisely where all of their facilities are due to intel from recent defectors who worked on the programs as well as humint and satellite information.
The only thing that needs to be demonstrated is whether we have the will.
"Axis of Evil" nation? Now is the time to see if our actions match up with our macho words before Congress and the world.