Trump is committing deterrence malpractice—in four ways.

The first is making threats so obviously hollow that many of his own advisers don’t believe or support them. First there was the tweet about not letting North Korea get a nuclear weapon that could reach the United States. Kim has now tested a long-range missile capable of hitting Los Angeles and possibly reaching as far as Chicago, and claims the weapon it just tested could fit on such a missile. (U.S. intelligence officials have indeed assessed that Pyongyang has succeeded in the difficult task of miniaturizing a nuclear warhead.) Trump at that time warned that he was “sending an armada” steaming toward the Korean peninsula—except that the “armada” was actually steaming in the opposite direction for a pre-planned exercise with the Australian Navy. More recently Trump channeled his inner Kim Jong Un to warn the real Kim Jong Un that North Korea would be “met with fire and fury like the world has never seen” if it kept threatening the United States. So Kim made some actual fire and fury.

George Shultz likes to say he learned one of his most important diplomatic lessons when he was a young Marine Corps recruit: Never point your rifle unless you intend to pull the trigger. The one iron law of deterrence theory, the one point on which nearly all scholars and policymakers agree, is the importance of credibility. The more you have it, the more you can coerce successfully—getting others to do what you want them to do. Undermine your own credibility with one, and you risk undermining your credibility with many. In Game of Thrones, nobody believes Theon Greyjoy will do what he promises. Everybody believes Ramsay Bolton will. The same is true in real-life contests for power across borders. Researchers have found that countries will go to extraordinary lengths to preserve their credibility, even fighting wars they know they will lose, so that others in the future know they mean business.

Trump’s second form of deterrence malpractice is that he conflates power with influence. Sure, the U.S. is orders of magnitude more powerful than the Hermit Kingdom on every dimension. America ranks among the richest nations in the world. North Korea is among the poorest. America created the internet. North Korea has 28 websites. America has the world’s most powerful military and spends more on defense annually than the next several nations combined. North Korea has somewhere around two dozen nuclear weapons and a starving populace. America has now-troubled but historically strong alliances and relationships with more nations around the world than any other country. North Korea has half a friend: Beijing. But history tells us that sheer power is often not enough: The most powerful side in a contest of threats frequently doesn’t win. The U.S. had more military, economic, and political power than Japan in 1941, Vietnam in 1965, Iraq and North Korea in the 1990s, and Pakistan after 9/11. And yet, American leaders were unsuccessful in preventing Japan’s entry into World War II, gaining victory in Vietnam, keeping North Korea from leaving the nuclear nonproliferation treaty, convincing Iraq to withdraw from Kuwait without resorting to war, or winning Pakistan’s full assistance in countering terrorism, including the hunt for Osama bin Laden.