It's astounding how much the world has changed since the end of World War II. Those 60 years have brought us television (now delivered via satellite in high definition), jet air travel (at close to the speed of sound) and the Internet.

These advances make it all the more surprising that the number of nuclear powers has barely changed. Until 1998, only the five permanent members of the United Nations Security Council -- Britain, China, France, Russia and the United States -- officially had "the bomb." That year, India and Pakistan joined the club.

One key reason there are so few is that the United States has worked hard to prevent others, including our allies, from going nuclear. For decades, we've promised to protect Europe and Asia in the event of an attack, and our allies count on that. Countries including Germany, Japan, South Korea and Taiwan -- all wealthy enough and technically able -- don't have nuclear weapons. When Taiwan and South Korea undertook secret nuclear-weapons programs in the 1970s and 1980s, the United States exerted enormous economic and trade pressures to force them to cease.

But now the equation is changing. In recent years North Korea has made clear that it wants nuclear weapons as soon as possible. "Dear Leader" Kim Jong Il has even replaced his father's "juche," or "self reliance" ideology with "songun," or "army first," a frightening doctrine that makes the entire nation subordinate to the military and demands that the army have "the most advanced" weapons.

North Korea is, in reality, nothing more than a failed experiment. The power flickers on and off. It features wide boulevards and skilled traffic cops, but almost no cars. It depends on foreign aid to prevent mass starvation. It's one of the last countries fighting on the losing side in the Cold War.

The "Dear Leader" clearly thinks that having nuclear weapons gives his regime an international legitimacy it can't earn otherwise, so he's been dragging out the six-party talks aimed at convincing it to end its nuclear program. But the most important country in those talks isn't North Korea or the United States. It's China.

China provides most of North Korea's fuel and food. Without Chinese support, it's likely that North Korea would have collapsed long ago. So when Pyongyang speaks, it's safe to assume it's speaking with Chinese support.

For years now, China has let the North Koreans bluster about their nuclear ambitions. That may be because North Korea takes verbal shots at the United States that China, as a major trading partner, can't take. For example, a North Korean newspaper recently wrote, "[President] Bush is the world's worst fascist dictator, a first-class warmaniac and Hitler, Junior, who is jerking his hands stained with blood of innocent people."

But the Chinese may be starting to realize that a nuclear North Korea isn't in their best interests. "The appearance of nuclear weapons on the Korean Peninsula does not serve the interests of the region and any country in the world," Foreign Ministry spokesman Liu Jianchao said recently.

That's the key point. China enjoys watching the North Koreans thumb their noses at the U.S. But if Pyongyang goes nuclear, Beijing is much closer to the potential fallout. China shares a border with the North Koreans, and "Dear Leader" Kim Jong Il is famously unpredictable. The Chinese are right to worry that their protégé might end up using his nuclear toy against them.

Plus, if North Korea goes nuclear, the region's democracies probably will, too. South Korea and Japan would have little choice but to take defensive measures, especially since North Korea already has test-fired a missile over Japan. If North Korea justifies nuclear-weapons programs by pointing to some American threat, what's to prevent Taiwan from claiming that Beijing's recent "anti-secession law" requires a similar reaction?

Every nation has to adjust its foreign policy so that it continues to serve the specific regional interest of its people. Historically, the best defense against a foe with nuclear weapons has been to build your own. Japan already has the nuclear reactors, the technology and the money to build nuclear weapons. South Korea and Taiwan aren't far behind. No doubt all three could turn out nuclear weapons more quickly and efficiently than North Korea could.

Imagine that you're China's leader, Hu Jintao. You're bordered by nuclear Russia, Pakistan and India. Would you really want to add a nuclear Japan or South Korea? Worse still, would Mr. Hu want to see Taiwan adopt a North Korean strategy of survival?

So the future's up to Beijing. It can either use its influence to block North Korea or accept that the U.S. would let our allies protect themselves with nuclear weapons. That's a future we'd all prefer to avoid.

Ed Feulner is president of the Heritage Foundation.