Here's What You Need to Remember: Nobody wants to see such a man-made disaster occur. It would a terrible, terrible waste of human potential and a moral travesty.

North Korea is the most difficult of targets for the U.S. intelligence community to unearth. Intelligence collection and analysis is an incredibly time-consuming and dangerous business, where it often takes months and maybe even years of patient rapport-building (and in some cases, blackmail) to recruit an agent or flip an adversary. The Central Intelligence Agency, the National Security Agency, and the Office of the Director of National Intelligence don’t have that luxury with North Korea. What Washington does have is satellite imagery from above and electronic interception, but even Director of National Intelligence Dan Coats confessed to the Senate Intelligence Committee that “using that as an access to collection is—we get very limited results.”

We do, however, know one thing for certain: in the crazy scenario whereby Kim Jong-un orders his nuclear forces to launch a nuclear-tipped ICBM towards an American city (one, by the way, that would rest on the supposition that Kim is a lunatic who believes Washington would back down after an attack), President Donald Trump wouldn’t hesitate to retaliate with the “fury and fury” of America’s nuclear weapons arsenal. There probably wouldn’t even be a debate with Defense Secretary Jim Mattis, National Security Adviser H. R. McMaster, or U.S. Strategic Command commander Gen. John Hyten. And if there was a discussion, it would focus on where, not whether, to hit North Korea.

Pyongyang, the capital city where millions live, would be the obvious target for a retaliatory nuclear strike. Kim Jong-un would likely be scurried away in a bunker somewhere with his sister and his senior generals long before Washington gave the order to the men and women who manage the U.S. nuclear triad to execute a launch, but that wouldn’t really matter. The purpose of a U.S. retaliatory attack would be to create so much destruction on North Korea’s military chain-of-command, its minuscule economy, its hereditary political system, and its physical existence as a nation that Kim Jong-un wouldn’t continue throwing nukes at the problem. Ideally, he wouldn’t have any more nukes to launch.

Using Alex Wellerstein’s NukeMap algorithm website, I attempted to determine the extent of the destruction in human terms if the United States targeted the center of Pyongyang with a single 750-kiloton device (the largest nuclear device the United States possesses in its arsenal is the B83 with a 1.2 megaton yield). Because Pyongyang is a sense city—denser than Los Angeles, which is a major urban sprawl—one blast of a nuclear device with that magnitude would kill over 1.5 million people. Taking UN population statistics into account (25.281 million), one 750-kiloton nuclear blast in downtown Pyongyang would wipe out nearly 6 percent of the North Korea’s total population. To better comprehend the deep extent of that damage for North Korea, that would be like killing 19.27 million Americans in one day from one attack.

Add estimated injuries into the equation (855,410), and the casualties would rise to over 2.3 million.

As to which structures in Pyongyang would cease to exist and which would only suffer moderate damage, take a look at the map. The workers and visitors of the Victorious Fatherland Liberation War Museum in northwest Pyongyang would have a 50 percent to 90 percent chance of dying within the first hours, days or weeks from the radiation exposure. Receipts at the Kaeson Youth Park slightly to the northeast would be killed as concrete buildings collapsed. Across the Taedong River, the Ideals of North Korean Workers facility would have the same bloody ending. The thermal radiation radius, the outer ring of the yield, where people would be dealing with third degree burns requiring possible amputations, would extend 11.1 kilometers in all directions. Pyongyang’s skyline wouldn’t really be a skyline anymore; all those fancy skyscrapers that Kim spent so much money on would be a wasted investment.

Nobody wants to see such a man-made disaster occur. It would a terrible, terrible waste of human potential and a moral travesty. Any nuclear attack anywhere in the world would expose the hollow progress of human civilization, that despite all of the technology and medical advancements made over centuries, humans in the twenty-first century are as primitive as cavemen.

But North Korea should be under no illusions. If it were irrational enough to send a nuke towards an American city, then it better anticipate its demise as a nation. Donald Trump wouldn’t accept anything but forceful retaliation—no American president would.

Daniel DePetris is a fellow at Defense Priorities. This article first appeared two years ago.

Image: Reuters.