Today, North Korea threatened to unleash “unprecedented nuclear strikes” on the United States and South Korea. The reason for Pyongyang’s extreme unhappiness? Washington and Seoul are making plans about what to do should the North fall apart. Kim Jong Il’s regime called the possibility of internal unrest a “pipe dream.”

It’s not. The Democratic People’s Republic of Korea seems, once again, to be in terminal decline—and perhaps on the verge of collapse. Collapsing regimes often execute their own officials for policy mistakes, and that’s what North Korea is doing now.

Pak Nam Gi, the official held responsible for last November’s botched demonetization of North Korea’s currency, was reportedly executed this month by firing squad. The finance and planning department chief of the ruling Workers’ Party paid a high price for the economic chaos and social turmoil that followed the regime’s desperate attempt to confiscate the wealth of private traders and gain control of informal markets.

Pak’s currency move was so disastrous that there are now reports of starvation deaths—even in a relatively prosperous area bordering China—and stories of malnourished beggars in the capital city of Pyongyang.

There has also been a rash of public executions for economic crimes. In December, for instance, a citizen was put to death for burning old currency to hide prior market activities. In January, a factory worker faced a firing squad for talking about the price of rice on cell phone to a South Korean.

So will the system headed by Kim Jong Il collapse soon? New reports, including one released this week from the East-West Center in Honolulu, indicate growing instability within the world’s most isolated state. The unexpected protests following last November’s currency “reforms” have persuaded analysts that the DPRK could see what is politely termed “discontinuous political change.”

And there is much to suggest a change in the form of government soon. In Pyongyang, at the moment, there is a one-man regime headed by a sickly individual sponsoring an unpopular secession plan to take over an increasingly discontented society. North Korea, despite its weapons of mass destruction, is a weak state.

But perhaps not as weak as experts think. For all the problems plaguing the North, the Kim family regime has something even better than an ace in the hole. And what is that?

That is China. Ever since both states were formed—the Korean people’s republic in 1948 and the Chinese one in the following year—they have been allies. Mao Zedong famously said China and North Korea were “as close as lips and teeth,” but in some ways there is even less distance between the two countries today. In Mao’s time, Kim Il Sung, the DPRK’s founder, maintained independence by playing Moscow off against Beijing. Now, however, strongman Vladimir Putin is not interested in engaging in that game, and as a result, Kim Jong Il has only one sponsor.

Perhaps that’s the reason the North Korean leader made the trip to the tarmac and hugged Wen Jiabao on the Chinese premier’s arrival in Pyongyang last October. Another reason—undoubtedly more important in Mr. Kim’s mind—is that Wen came to sign commercial pacts and to dispense aid. Xinhua, the official Chinese news agency, stated that the two communist states “signed a series of agreements on cooperation and announced that a new highway bridge over the Yalu River will be built.” It appears Beijing also agreed to provide financial assistance to Kim’s destitute state, perhaps as much as $200 million.

Mr. Wen’s visit to the North was ostensibly to celebrate sixty years of diplomatic ties, but his real goal was to buttress Kim’s economy. China’s trade with its communist cousin soared since Pyongyang’s first nuclear test in October 2006. For instance, commerce with the Chinese increased 41.3 percent in 2008. This spurt was instrumental in helping Pyongyang end the two-year recession of 2006 and 2007. China-North Korea trade fell off in 2009—down about 4 percent according to preliminary figures—but the agreements announced by Premier Wen in October helped put trade back on course toward the end of the year.

China is not only aiding the North Korean economy—it is also helping the North militarize the atom. Unfortunately, a growing share of the China trade is channeled through business enterprises directly controlled by the Korean People’s Army, which is expanding its grip over the economy. Therefore, the connection between China’s commercial ties with Pyongyang and its nuclear weapons program is tight. That is undoubtedly one of the reasons that led Seoul, immediately after Wen’s trip to Pyongyang, to ask Beijing for an explanation of the announced commercial pacts.

On their face, the deals appeared to violate U.N. Security Council Resolution 1874, unanimously adopted last June in the wake of the North’s second nuclear weapons test. Paragraphs 19 and 20 of the resolution forbid many, if not most, commercial contacts with Kim’s Korea.

If the October 2009 raft of agreements did not violate Resolution 1874, then later developments surely did. Two of them in particular stand out. First, Beijing in February reportedly pledged $10 billion in investments into North Korea. Second, earlier this month the Chinese announced they would extend their lease on North Korea’s Rajin port, on the Sea of Japan, for another 10 years. The port could end up serving as a base for China’s navy. In any event, Beijing is sanctions busting, giving the North the means to continue its nuclear weapons program and forestalling the need to disarm.

At a crucial moment, China is throwing a lifeline to Kim Jong Il. North Korea is an increasingly fragile state. But with Beijing’s help, it will probably survive to once again threaten the United States with nuclear destruction.

Gordon G. Chang is the author of "The Coming Collapse of China." He writes a weekly column at Forbes.com.

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