How are we to make sense of the president of the United States—a man with unitary launch authority for over a thousand nuclear weapons—going before the United Nations General Assembly and threatening to annihilate a sovereign state? That’s exactly what President Donald Trump did on Tuesday, halfway into a long, winding speech on everything from sovereignty to UN funding. “The United States has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea,” Trump read carefully from his teleprompter. In one breath, he touted the virtues of the nation-state and sovereignty and, in another, promised the utter destruction of a sovereign state.

While Trump’s apocalyptic rhetoric and threat to commit a horrific act expressly forbidden by international humanitarian law will surely go down in General Assembly history, their underlying logic is undeniably familiar. The remarks echoed similar, countless deterrent threats levied against North Korea by past U.S. presidents with more subtlety and innuendo, perhaps allowing for a more calibrated and flexible response. But ultimately vowing to “totally destroy” North Korea if America or its allies come under attack is, in fact, not all that sharp a break from existing U.S. policy.

That familiarity, however, shouldn’t obscure that this kind of posturing is precisely the kind of rhetorical exercise that can exacerbate North Korea's insecurity and lead to deadly miscalculation—miscalculation that would, now, almost certainly expose Americans, South Koreans, and Japanese, to nuclear attack.

Unlike Trump’s off-the-cuff August promise to respond to continued threats from Kim Jong Un with “fire and fury,” his latest words were presumably the product of interagency coordination—or at least considered speechwriting reflecting policy. As a result, they reflect a bona fide U.S. position. “Rocket man is on a suicide mission for himself and for his regime,” Trump added in his speech, using his nickname-of-choice for Kim.

Why is Trump so seemingly vexed by North Korea? His speech came within weeks of Kim’s test of what was allegedly a compact thermonuclear device, which yielded an energy level an order of magnitude greater than the regime’s previous nuclear tests. Moreover, last week, for the first time ever, North Korea demonstrated its ability to fly a ballistic missile—one perhaps capable of carrying precisely the nuclear device that it claimed to have tested—to the U.S. territory of Guam. The test was also the second ballistic missile launch by North Korea to overfly Japan's territory. (North Korea had previously only launched satellite launch vehicles over Japanese territory.)

North Korea knows that a nuclear attack against the United States or its allies would lead to massive U.S. nuclear retaliation — total destruction, in other words.

For anyone even peripherally aware of North Korea’s bellicosity, none of this is new. The Kim regime is a loathsome and serial violator of human rights, leaving its people’s interests subservient to its pursuit of what it sees as absolute security under a nuclear umbrella. But the world has dealt with all of this before. Over multiple administrations, senior U.S. officials, including presidents, have threatened to bring grievous harm to North Korea should it ever initiate a war against America or its allies. President Barack Obama, in his first summit with former South Korean President Park Geun Hye in 2013, noted that the United States would defend its ally with the “full range of capabilities available, including the deterrence provided by [its] conventional and nuclear forces.” Similarly, senior U.S. officials regularly promise an “effective and overwhelming” response to any use of nuclear weapons against the United States or its allies by North Korea.

That phrase was emphasized last year by Ash Carter and John Kerry, the then-secretaries of defense and state, respectively, and repeated recently by their successors, Jim Mattis and Rex Tillerson, in a recent Wall Street Journal op-edoutlining Trump’s North Korea policy. Clarifying that there are conditions under which North Korea would elicit its own destruction at the hands of the United States, then, has been a part of how Washington talks to and about North Korea. North Korea knows that a nuclear attack against the United States or its allies would lead to massive U.S. nuclear retaliation—total destruction, in other words. These threats, while undoubtedly gruesome, serve two important strategic ends: They reinforce deterrence against North Korea and reassure America’s allies that, if attacked, they would be backed by Washington’s full military might—including the nuclear weapons at its disposal.

The use of the conditional “if” in the above statements, and even in Trump’s General Assembly speech, is critical, as was what came before it. That’s why his promise of “fire and fury,” implying that the United States would use nuclear weapons first against North Korea in response to mere threats rather than specific actions, were of such concern.

But Trump’s remarks at the General Assembly are cause for concern, too. “Fire and fury” aside, official U.S. language has, of late, grown both more apocalyptic in style and less clear in substance—with implications for deterrence stability. On August 9, for example, on the 72nd anniversary of the nuclear bombing of Nagasaki by the United States, Mattis released a statement noting that North Korea “should cease any consideration of actions that would lead to the end of its regime and the destruction of its people.” Ultimately, these cavalier threats—some euphemistic and some less so—to “destroy” a country of 25 million people are a reminder of the dirty business that underpins nuclear deterrence and brinkmanship.

Both McMaster and Trump are wrong about the Rocket Man. He tests his missiles for entirely rational reasons.

As Thomas Schelling observed decades ago, the possession of nuclear weapons meant that “Military strategy could no longer be the science of military victory.” Instead, strategy “would be the art of coercion, intimidation and deterrence.” The implication: Telling your adversaries exactly how you’ll harm them and for what behaviors can be the clearest incentive for them to steer clear of those behaviors.

But let’s be real. Trump’s statement wasn’t a considered attempt at establishing what Schelling called the “balance of terror” between the United States and North Korea. Arguably, the threats of “effective and overwhelming” responses have communicated the consequences of any attack to North Korea now for years; if Pyongyang is familiar with America’s credible threat of massive nuclear retaliation, why rock the boat at the UN with needless braggadocio? Trump's remarks must be considered along with his administration's bumbling signaling to Kim, which has given him the impression that everything—ranging from direct diplomacy with fewer preconditions than the Obama administration imposed, to a preemptive strike—remains “on the table.”

Most importantly, however, it’s impossible to make sense of Trump’s threat without considering that second sentence, which implied that Kim—the “Rocket Man”—is on “a suicide mission for himself and for his regime.” The concept of suicide, when applied to nation-states and regimes, comes with a strong implication: That they do not seek survival above all else. Extending that reasoning, a nation-state that does not seek survival but instead seeks suicide cannot be deterred with threats of total destruction. If Kim Jong Un is indeed “suicidal” in his pursuit of nuclear weapons and missiles, he is presumably irrational and, as a result, cannot be deterred.

Trump’s advisors have also intimated that Kim may be similarly irrational. H.R. McMaster, his national security advisor, recently argued that his brutality meant that “classical deterrence theory” didn’t apply to him—never mind that Mao Zedong’s China and the Soviet Union were similarly repressive and characterized as rogue, unstable regimes. Nevertheless, they were deterred.

Both McMaster and Trump are wrong about the Rocket Man. He tests his missiles for entirely rational reasons. Not only does he seek survival above all—that's his entire reason for building a nuclear arsenal in the first place. As an editorial in North Korea's state-run Rodong Sinmun observed in August, the regime’s core takeaway from the submission of Iraqi leader Saddam Hussein and Libyan leader Muammar Qaddafi to disarmament efforts—and their ultimate fates—is that “nuclear possessors did not suffer military aggression.” Kim calculates that as soon as he’s able to place that nuclear device he tested on September 3 on the intercontinental-range missile he first tested on July 4 and fly it to the contiguous United States, his survival is guaranteed. That’s how he wins: by forcing Trump into a corner where initiating a regime-change war seeking North Korea’s “total destruction” would instead put Washington on a “suicidal” course. It’s unclear if Trump and his advisors understand this just yet. The repeated threats suggest they either don't or are content to erode U.S. credibility for little reward.

If sanctions don’t change North Korea’s behavior, and if diplomacy is unpalatable to Trump, and war is an unacceptably costly option, the most likely path is for deterrence to continue to hold between Washington and Pyongyang. Allowing that to happen will not only require the Trump administration to take North Korea's capabilities seriously, but to communicate its own deterrent threats as clearly as possible.

If Trump wanted to reinforce deterrence with North Korea at the General Assembly podium, all he need to do was succinctly communicate that any use of nuclear weapons would elicit the standard “effective and overwhelming” U.S. response. We know what that means; North Korea does, too. And so do U.S. allies. Instead, Trump delivered another round of inelegant and potentially destabilizing messaging that will only harden Kim’s resolve to continue apace with his ballistic missile and nuclear weapons development, and heighten the prospects for catastrophic miscalculation.