SEOUL, South Korea -- North Korea will negotiate only with the United States to end the standoff over its nuclear program, an envoy from the North said Friday, rejecting the idea of multilateral talks on the dispute.
The new position came as U.S. officials said North Korea appeared to be gearing up at its nuclear facility at Yongbyon. American spy satellites detected substantial activity at the facility in January -- a sign the country may be getting ready to produce nuclear weapons.
White House spokesman Ari Fleischer would not comment on U.S. intelligence, but warned Pyongyang against taking "another provocative step" that "further isolates North Korea from the international community."
The United States has sought to bring the issue before the United Nations, and has encouraged efforts by Russia, China and South Korea to help resolve the standoff.
The U.N. International Atomic Energy Agency has scheduled a meeting on the crisis on Feb. 12.
But North Korea's envoy to China said the United States was alone to blame for the dispute and flatly rejected the possibility of involving other countries in the talks.
"Only the U.S. is responsible for doing away with the threat and able to do so," Choe Jin Su said at a news conference in Beijing.
Choe repeated his government's demand for a nonaggression treaty with the United States. Washington has ruled out such a treaty but says it has no intention of attacking North Korea and could provide a written security guarantee.
North Korea took its first steps to reactivate Yongbyon last fall after Washington and its allies suspended oil shipments to North Korea, which in turn expelled U.N. nuclear inspectors and pulled out of a global nuclear arms control treaty.
Washington said North Korea had admitted having a nuclear weapons program in violation of a 1994 agreement.
International attention has since focused on whether the North will remove spent nuclear fuel rods from the cooling pond at Yongbyon, where they had been kept safely under the 1994 agreement, and transport them into a reprocessing plant that experts say will extract enough plutonium for several bombs in a matter of months.
On Friday, U.S. officials said American spy satellites have detected covered trucks apparently taking on cargo at Yongbyon.
It is possible -- but not certain -- that the trucks seen at the plant are loading those rods, either to be stored elsewhere or in preparation for processing, one official said.
Mohamed ElBaradei, head of the Vienna-based U.N. nuclear watchdog, said North Korea could have a "significant" amount of nuclear material within six months.
He called the North's work at the reprocessing plant "a matter of grave concern" and said he hopes an emergency board meeting to deal with the North Korea crisis will take place Feb. 12 despite some disagreement among member states on the date.
"I've already submitted the report to the board saying that North Korea is in noncompliance. So we need to get the board to certify that conclusion," he said.
"We obviously then have to report in accordance with our charter -- our statute -- to the Security Council," ElBaradei said at the Vienna airport upon arrival from New York.
The U.N. nuclear watchdog had previously suggested a Feb. 3 meeting, but South Korea wanted to delay the meeting to give North Korea time to change course.
North Korea's ambassador to Moscow said in Russia on Friday that his government would ignore the Feb. 12 meeting and accused the U.N. agency of serving the U.S. interests.
If the Security Council takes up the issue, it could lead to sanctions against the North, though Pyongyang has said it would view sanctions as a declaration of war.
Deepening the crisis, North Korea on Thursday condemned President Bush for his State of the Union address, in which he called North Korea "an oppressive regime" ruling "a people living in fear and starvation."
"Bush has so far earned an ill fame as an emotional backbiter, but his recent address clearly proves that he is a shameless charlatan reversing black and white under the eyes of the world," a North Korean Foreign Ministry spokesman said in a report by the country's news agency KCNA.