Indeed by late last week, when U.S. officials grew increasingly certain that North Korea would detonate a nuclear device, there was a sense of resignation in Washington—almost a feeling of relief that, at long last, strategic clarity had arrived. “At least there would be a unified front against North Korea” if Pyongyang tested, one senior official told NEWSWEEK on Friday. “And it would light a fire under some parties.” He was referring to China. For the last year Washington had effectively subcontracted nuclear negotiations to Beijing, which was given the lead in the “six-party” talks that pitted Pyongyang against the United States, China, Russia, Japan and South Korea. China was key because, as Pyongyang’s longtime ally, it held the strongest hand against North Korea, controlling more than 70 percent of its energy supplies.

But U.S. officials had become increasingly frustrated by China’s reluctance to squeeze Pyongyang harder. In the past, even when it was displeased with Kim, Beijing has done little more than temporarily interrupt fuel flows. The hope in Washington is now that Chinese President Hu Jintao will decide he’s finally had enough of his out-of-control former junior partner. With Sunday’s test Kim has now twice rebuffed Hu’s pleas for restraint. The last time was July, when Kim ignored the Chinese leader’s request not to test missiles. This time Kim insulted Hu the day after an important Sino-Japanese summit with Tokyo’s new prime minister, Shinzo Abe—a nationalist who will no doubt be probing China’s strategic determination—and on the eve of a big communist party plenary session at which Hu’s reputation will be on the line.

For Washington, almost everything is riding on this hope. U.S. officials are talking tough about beefing up their Proliferation Security Initiative, which mainly involves interdicting suspect shipments on the high seas. But last week they quickly walked back any speculation that Assistant Secretary of State Christopher Hill’s stark rhetoric from last week—“North Korea can have a future or it can have these weapons. It can’t have both,” Hill said—meant a threat of war. The Pentagon is extremely leery of any military options, with the heavily-populated South Korean capital of Seoul lying vulnerable to missile attack just across the North Korean border. What Hill’s comment meant instead, several U.S. officials said, was that the U.N. Security Council would move to impose sanctions, and key countries such as China, Japan and South Korea would join in, ensuring that the Pyongyang regime remains utterly friendless.

So friendless, in fact, that it dies of loneliness. Bush administration officials will not concede this publicly, but hardliners in Washington have long been pushing for a policy of regime change against Pyongyang. President Bush himself subtly underlined that threat when, at a Monday morning news conference, he said “the oppressed and impoverished people of North Korea deserve” a “brighter future.” Hence, only days after China orchestrated a framework agreement in September 2005 that promised the North it would be rewarded if it abandoned its nuclear program, including with a civilian nuclear reactor, the Bush administration imposed sanctions on the Macao-based Banco Delta Asia that effectively froze the accounts of Kim and other North Korean elites. The action is believed to have so riled Kim that he refused to return to the talks.

Now the hardliners have won the day. There are unlikely to be any carrots offered for quite a while to Kim after he posed what President Bush on Monday called “a threat to international peace and security” that “defied the will of the international community.” Still, Washington is gambling on quite a number of still-untested premises. It is gambling that Hu Jintao will be angry enough to sponsor a strategic shift in his country’s view of North Korea; until today Beijing has been reluctant to do anything that might lead to regime collapse. And it is gambling that the regime itself is moribund.

The problem there is that Bush administration officials have always underestimated the peculiar staying power of North Korean totalitarianism. There is, in fact, a reason why the regime created by Kim’s father, Kim Il Sung, and perpetuated by the son survives while Marxism-Leninism has become a yellowing chapter in the history books elsewhere (even next door in China, which nominally retains its communist ideology while economically it has embraced capitalism like a zealous convert). The North Korean regime’s ideology, called juche , is often simplistically defined as Korean self-reliance and ridiculed in the West. But to the North Koreans, juche is a powerfully intoxicating brew of traditional Korean xenophobia and nationalism, Confucian respect for authority and utopian Marxism-Leninism. The result is “an impermeable and absolutist state that many have compared to a religious cult,” longtime Korea observer Don Oberdorfer wrote in his 1997 book, “The Two Koreas.”

U.S. officials prefer to see the North Korean regime as a brutal criminal enterprise, one that certainly cannot be tolerated as a nuclear power. The question now is whether Washington can persuade the rest of the world—especially China—to take that view as well, and whether together they have the ability to precipitate the destruction of the regime without taking military action. If not, the world must reckon with a new, and potentially very dangerous, nuclear power.