North Korea has sentenced four South Korean journalists to death for reviewing a two-year old book, North Korea Confidential.

That book explores the hidden capitalism thriving at the heart of the North Korean economy and political structure, and was written by two British journalists who, so far, they have escaped absentee death sentences themselves.

Still, announcing its verdict, the North Korean judiciary didn't hold back. "Not content with viciously slandering our socialist system, the most advantageous system centered on the popular masses which can not be found in any other parts of the world, they seriously insulted the name and emblem, symbols of the inviolable dignity of the [Democratic People's Republic of Korea]. This is a never-to-be-pardoned high treason." The book, it said, is "a collection of words uttered by the riff-raffs including defectors from the north..."

And in a clear threat to carry out assassinations on South Korean soil, the North Koreans affirmed that "The criminals hold no right to appeal and the execution will be carried out any moment and at any place without going through any additional procedures as soon as the objects are confirmed. We will track down to the end those who masterminded and manipulated hideous provocations of slandering and insulting the dignity of the DPRK and mete out death to them."

In case the flamboyant language hadn't carried the point through, the judiciary spokesman attacked "... the group of wicked conservatives who are breathing their last after being reduced into a group of living corpses."

Phew!

That said, in North Korea's fury here we see the insecurity and hypocrisy that lies at the heart of Kim Jong Un's regime. Our appreciation of those realities is important.

First off, as Bradley Martin accounts in his book, Under the Loving Care of the Fatherly Leader, the Kim dynasty has long flirted with various capitalist reforms. They have done so for two reasons: to boost economic output and thus generate capital for the regime, and to placate inner-party citizens with access to more luxurious goods and services.

Sometimes, as when it comes to some commercial activities such as its foreign restaurant chain, the regime is unconcerned with public attention. Those restaurants, after all, have the excuse of propaganda: promoting the beauty of the North's ideology and society to a global audience. It's also notable that Kim Jong Un embraced bold economic reforms on taking power in late 2011. He appears to have recognized that the North's pathetic economic output threatened his own survival as leader: that in order to maintain the loyalty of the elites, he would have to buy some off.

Yet the Kim dynasty cannot be too open about its capitalist flirtations. That's because it lives in a perpetual catch 22. Embracing its "Juche" ideology of self-sufficiency alongside an avowed hatred of capitalism, Kim Jong Un can't admit the scale of his experimentation. The death sentence reflects a deep insecurity born of immense hypocrisy.

Nevertheless, the balancing act that isn't going away. Consider how North Korea employs its diplomatic corps. Knowing that many diplomats will never want to return home once they go abroad, North Korea allows its diplomats to get rich while generating money for the regime via criminal enterprises. It's the height of hypocrisy, and a necessity of the regime's functionality.

All this said, the North isn't just upset with the book reviewers this week. On Thursday, officials also threatened South Korean journalists who repudiated North Korea's threats to Guam. "We will track down," it warned, "the puppet conservative reptile writers fostering discord within the nation under the auspices and at the instigation of the anti-reunification forces at home and abroad, and throw all of them overboard."

Such words make it easier to understand why the Trump administration doubts Kim Jong Un's deterrability.