So we did. In documents and interviews, we found plenty of evidence that North Korea was a target; the hard scientific problem was determining whether the cyber and other electronic attacks — and not engineering incompetence or insiders working for the West — were actually responsible for the failed launches. With more digging, we arrived at some theories about the mechanics of how it was all happening.

Then came the sensitive part of these investigations: telling the government what we had, trying to get official comment (there has been none) and assessing whether any of our revelations could affect continuing operations. In the last weeks of the Obama administration, we traveled out to the director of national intelligence’s offices: a huge complex in an unmarked office park a few miles beyond the C.I.A.’s headquarters in Fairfax County, Va. Such conversations are always fraught. Understandably, government officials don’t want to confirm or deny anything — in fact, they can’t. But it’s still important to listen to any concerns they might have about the details we are planning to publish so that we can weigh them with our editors.

I had been distracted by other stories — including a reconstruction, in collaboration with my colleagues, of the Russian hack of the election — so our reporting continued past Inauguration Day. That meant it would need to incorporate President Trump’s options for dealing with the North Korean threat. It also meant going through those discussions about the program again, this time with a new administration whose key officials had barely had time to understand their new jobs, much less develop a Korea strategy. Like the Obama officials we dealt with before them, they engaged the subject deeply and professionally.

As Dean often says, we do not take lightly the publication of secret information, especially in national security cases. We also fully expect that the government’s first reaction will usually be some variant of: “You shouldn’t print anything, because the subject is so sensitive, the diplomacy so delicate and the reaction of nations like North Korea so unpredictable.”

We take a somewhat different view: If America is going to have an informed public discussion about how to deal with the nation’s most looming threats, this kind of investigative journalism is essential. In this case, that meant uncovering, and explaining, both the dimensions of North Korea’s nuclear program and the American struggle to defeat it. If America’s old concept for missile defense isn’t working and if throwing high-tech malware at the North Koreans isn’t a silver bullet, those are critical facts about the choices a new president faces.

We’ve been there before: At the height of the nuclear arms race, The Times covered the debate over nuclear strategy, including what kind of global rules should be established to govern how the world’s most terrible weapons are controlled, without delving too deeply into the “how” of building a bomb. The same careful navigation is necessary when it comes to cyber attacks.

Our story went through dozens of drafts, as we tried to make an enormously complicated subject clear. In the Washington bureau, Bill Hamilton, who oversees national security reporting, turned his editing talents to helping us shape a narrative that mixed news, analysis and a long history of efforts to deal with a North Korean program that has bedeviled the last five presidents. David McCraw, the Times lawyer who is a veteran of many big stories on national security issues, read draft after draft to help us navigate a raft of complex issues. A talented team of graphics and photo editors put together a powerful package that helped explain the reach and progress of North Korea’s weapons programs. Translations were prepared in Korean and Chinese, giving the story a broader reach.

On Sunday, over the phone, Bill Broad said to me what he always says after a big project: “This was great. Let’s never do it again.” And then, of course, he started talking about where we might take the story next.