The United States and Asian countries have begun to accept the idea of a nuclear-armed North Korea, according to officials and analysts here and in Washington. Increasingly, the Bush administration is turning its attention to preventing the Communist government in Pyongyang from selling nuclear material to the highest bidder.

Envoys for the new South Korean president, Roh Moo Hyun, shocked Bush advisers in Washington recently when they said they would rather have a nuclear North Korea than a chaotic collapse of the government there, according to sources in Seoul.

And in Japan, located within missile range of North Korea, officials feel their neighbor cannot be stopped from producing a bomb. "We need to be debating how to live with North Korea, with or without nuclear weapons," Taro Kono, a lawmaker from the ruling party, said in an interview.

Washington had issued repeated warnings to North Korea not to begin reprocessing materials that could become fuel for a nuclear bomb, but administration officials have become resigned to North Korea taking that step sometime within the next two to four weeks. "The administration has acquiesced in North Korea becoming a nuclear power," said a Senate source who was briefed last week on the administration's evolving policy.

U.S. officials have begun to contend that a decision by North Korea to begin reprocessing spent nuclear fuel rods into weapons-grade plutonium will represent a diplomatic opportunity to swing international opinion to its side in the impasse over North Korea's nuclear ambitions, administration and congressional officials said today.

The administration thinks the shock of a decision by Pyongyang to export nuclear materials would force Russia, China, South Korea and other nations to drop their reluctance to confront the Communist state. According to that view, they would go along with the United States in mounting a tough campaign to further isolate the North and possibly to try to interdict suspected shipments of nuclear materials.

Production of plutonium that could flow abroad in clandestine sales "fundamentally changes the equation," contends an administration official. "Literally every city on the planet would be threatened."

During the last crisis over North Korea's nuclear ambitions, in 1994, the Clinton administration indicated to Pyongyang that reprocessing materials for a nuclear bomb could prompt a military strike. Many officials in Asia believe that Washington will now set new "red lines" that it will not tolerate North Korea crossing. But Bush and his senior advisers have refused to do that, publicly at least, saying it would only encourage North Korea to charge past them.

North Korea already is a major source of missile technology, and an Iranian resistance group recently said that North Korean experts are assisting Iran in its pursuit of nuclear weapons. Now officials worry about a new kind of export.

"Our major fear is that North Korea would pass on fissile material or other nuclear technology" to "rogue states" or outlaw groups, Deputy Secretary of State Richard L. Armitage warned Congress last month. "I don't think, given the poverty of North Korea, that it would be too long" before such sales took place, he said.

"The total red line is the sale of nuclear weapons material," said Rep. Mark S. Kirk (R-Ill.), who follows the North Korea issue closely. "Nuclear weapons transferred to the Iraqis would be tantamount to nuking Jerusalem."

The Senate source said the administration was playing "a very dangerous game" in not acting to stop reprocessing before it starts, because the resulting materials could be hidden in the country's network of caves awaiting export.

But administration officials argue they have no good military options for eliminating North Korea's nuclear capability. A surgical strike might neutralize the plutonium plant, but the country's effort to enrich uranium is proceeding at another, unknown site.

President Bush told reporters this week that he was still seeking a diplomatic solution and that a "military option is our last choice." He also said that he would seek to "accelerate the development of an anti-ballistic missile system" to counter a potential threat from North Korean missiles.

U.S. officials quietly dropped the phrase that the United States has "no hostile intent" toward North Korea in their talking points about a month ago, an official said. "It's clear North Korea has hostile intent to us," he said.

"I wouldn't rule out use of military coercion if North Korea crosses . . . red lines," said Michael A. McDevitt, a retired rear admiral and director of the Center for Strategic Studies in Washington. "The one I am most worried about is if they produce enough plutonium to start hawking it on the open market."

An administration official said Chinese officials have told North Korea that China would consider any attempt to produce nuclear weapons a "direct threat to Chinese national security." While the Chinese told U.S. officials that they made it clear to North Korea they would not accept such a step, the Chinese statement did not address reprocessing or foreign sales of the resulting materials.

Many strategists have long asserted that the United States, China and Russia would not allow a nuclear-armed North Korea because it could dramatically alter the power structure in northeastern Asia and lead to an arms race as both Seoul and Tokyo demanded nuclear weapons.

Increasingly, however, it appears that North Korea is determined to defy those wishes. "In a way we are wasting our time to talk about dialogue with North Korea," said Masashi Nishihara, president of Japan's National Defense Academy. "Only after they develop a nuclear program will they come to the table."

Kessler reported from Washington.