The reality of war with North Korea is almost too terrifying to imagine.

Experts say the North’s artillery could kill tens of thousands of civilians in Seoul, South Korea’s densely populated capital, within the first hours of a conflict. A protracted fight would lead to destruction on the Korean Peninsula on a scale unheard of since the Korean War in the 1950s, with millions of deaths on both sides.

The North’s nuclear missiles could easily reach Tokyo; most major American cities are also within their range. Imagine a nuclear strike on New York City — hundreds of thousands of Americans dead or irradiated in a catastrophe that would dwarf 9/11 by multiple orders of magnitude — and you start to understand what’s at risk here.

But here’s the genuinely scary thing. Numerous conversations with US policymakers, former US government officials, and experts all point to one disturbing conclusion: Far from being unthinkable, a war with North Korea is becoming more likely by the day.

“We are far closer to actual conflict over North Korea than the American people realize,” says Sen. Tammy Duckworth (D-IL), an Iraq War veteran and Purple Heart recipient. “Everything we’re doing shows a military that, in my personal opinion, has turned the corner ... the president is likely to make this decision [to attack], and we need to be ready.”

North Korea’s escalating behavior — most notably its recent 2017 tests of powerful nuclear bombs and intercontinental ballistic missiles — has prompted an extremely aggressive response from President Trump. He has threatened to “totally destroy” North Korea, and to respond to its missile tests with “fire and fury like the world has never seen.” He has tweeted that negotiations with the North have made “fools of US negotiators," that the secretary of state was “wasting his time” trying to talk North Korea, and that “only one thing will work” when it comes to fixing the North Korea standoff — seemingly implying a willingness to use force.

There are two reasons to take all of this saber rattling seriously. First, the president might mean what he says: There’s a real chance that he and some of his top advisers truly believe Kim Jong Un’s recent behavior proves that he can’t be deterred and that launching a military strike against now, before the North’s nuclear program gets any stronger, is the least bad option.

But even if they are just bluffing, North Korea’s leaders can’t be sure about that, because they don’t have a great read on American intentions. This could lead Pyongyang to conclude an attack is imminent even when it isn’t and attempt to preempt a US strike with its own attack — potentially kicking off a war nobody actually wants.

This doesn’t mean war is inevitable. Political and military leaders on both sides of the conflict have for decades understood how disastrous the fighting would be for everyone involved, and have chosen time and time again to back down in situations that looked like they could escalate into a full-scale conflict.

But Kim Jong Un’s provocations, and Trump’s angry and unpredictable responses, have combined to make the situation genuinely more dangerous than it has been in the past. And there seems to be virtually no serious public debate going on over how to stop things from going wrong.

“We should be worried,” says Mira Rapp-Hooper, a North Korea expert at Yale University. “Given the stakes we’re talking about, nobody should be comfortable.”

Why Trump may be willing to launch a catastrophic war

Rhetoric from the president, who has final and essentially unrestricted power to use force, suggests he is open to war with North Korea. But discerning actual policy decisions from Trump’s Twitter and public comments can be difficult. To get a deeper read on what the White House may actually be thinking, looking at two other sources is instructive: Trump’s top advisers and the US military’s actions.

Both are quite worrying.

Trump’s advisers are, in theory, supposed to prevent him from making any rash and potentially catastrophic decisions. National Security Adviser H.R. McMaster, for example, is a decorated three-star general and the author of a well-regarded book, Dereliction of Duty, which focuses on how President Lyndon Johnson’s advisers failed to warn him away from disastrous escalation in Vietnam. McMaster, of all people, should know the true costs of letting a president get into a war he isn’t prepared for.

Yet he has spent months arguing that the North Korean regime is not rational, meaning that it cannot be deterred by the threat of US military retaliation. That’s an important point: If McMaster believes that North Korea cannot be deterred by the threat of force, the only logical conclusion is that the US should strike before the North has more time to expand and improve its nuclear arsenal. And he has suggested publicly that war is in the offing.

The risk of war with North Korea is “increasing every day,” McMaster said in early December. “There are ways to address this problem short of armed conflict, [but] there’s not much time left.”

CIA Director Mike Pompeo, rumored to be the top pick for secretary of state after Rex Tillerson’s expected departure, has taken a similarly hawkish line — warning in July that the most dangerous part of North Korea’s nuclear weapons is “the character who holds the control over them” and suggesting that North Korean leader Kim Jong Un “might well have intent” to use those weapons against the United States.

These voices aren’t unopposed in Trump’s war cabinet; both Tillerson and Defense Secretary James Mattis have been more cautious in their characterization of North Korea. Tillerson is clearly marginalized in the White House, with rumors of his departure coming seemingly weekly, but there is a general sense among Trump Kremlinologists that Mattis has the president’s ear.

“If you believe that war is imminent, you’re going to want to get your shot in first”

Yet we can’t assume Mattis is reining in McMaster and Pompeo. For one thing, the president seems more inclined to agree with the hawkish voices on his staff than the cautious ones. For another, the normal interagency policy planning process that helps presidents make big decisions like this — where relevant experts from around the government weigh in — isn’t working well.

Due to both Trump, who has failed to appoint people to key positions in the departments of State and Defense, and Tillerson, who has done an extremely poor job managing America’s diplomats, the administration lacks vital input from North Korea experts. There is, for example, no ambassador to South Korea in place.

Trump nominated respected Georgetown professor Victor Cha to the post in mid-December, but Cha still has to go through the Senate confirmation process before he can start, a process that could take months. Positions of this significance are almost never left vacant this long; with them unfilled, Trump and his top decision-makers aren’t getting vital information that could push them off their dangerous path.

“Part of what’s concerning me about all of this is how few North Korea and Asia hands are in the proper political positions,” says Rapp-Hooper. “McMaster, who is not an Asia hand or a nuclear weapons expert, is running [the] national security process — but does not have an assistant secretary of state for East Asia.”

Perhaps the most ominous sign in all of this is that the US military seems to be taking steps to prepare for conflict in North Korea that go beyond their normal troop rotations.

Over the past year, the US military has been quietly ramping up its presence near the Korean Peninsula. The Washington Post’s Dan Lamothe reported in October that the US military was deploying classified “strategic assets” — most likely meaning “submarines, aircraft carriers, nuclear weapons or bombers,” per Lamothe — to the peninsula.

Around the same time, South Korean Defense Minister Song Young-moo announced that Washington and Seoul would step up “relevant cooperation” involving strategic assets, including “studies to improve deterrence against North Korea.” The two nations have held several previously unplanned military exercises in late fall and early winter 2017.

These public actions, according to people with direct knowledge of the US military’s thinking, reflect a real sense inside the Pentagon that the president might actually pull the trigger.

“There are more serious conversations [now] happening inside the Department of Defense about military action than had been happening earlier in the year,” Sen. Chris Murphy, who sits on the Senate Foreign Relations Committee, told me in early December. These preparations, together with the president’s rhetoric, have made him worried about “Trump’s willingness to launch a preemptive strike.”

His worries are very much shared by some outside experts.

“If McMaster [and] Trump are serious, God help us” says Kingston Reif, the director for disarmament and threat reduction policy at the Arms Control Association.

The Trump administration’s rhetoric makes North Korea more likely to attack the US

Of course, all of this rhetoric could just be a giant bluff.

Many informed observers think McMaster is too smart to actually believe that North Korea can’t be deterred, given that experts are virtually unanimous in believing the North has long been successfully deterred by the threat of American retaliation. On this view, the administration’s rhetoric is principally about trying to scare China, North Korea’s largest trading partner, which Trump has often blamed for the crisis. The ultimate aim would be for China to more aggressively deploy its immense economic leverage over North Korea to rein in Pyongyang’s nuclear program.

“I think it’s rhetorical ... a way of convincing third parties that we will not compromise,” Joshua Pollack, an expert on North Korea’s nuclear program at the Middlebury Institute of International Studies, told me.

It’s nearly impossible to tell from the outside if this read is right. If the entire point of the administration’s strategy is to convince other countries that the threat of force is credible, then the threat needs to seem, well, credible. Bluffs don’t work if your opponent knows you have a 2-7, to use a poker analogy; they need to believe that you’re holding two aces.

And therein lies the problem: Even if Trump is bluffing, the North Koreans can’t be sure of that. They have to take the possibility of a US attack seriously because the United States has more than enough firepower to topple their government. Trump’s aggressive rhetoric, whether serious or not, has put the North Koreans on high alert.

That in and of itself makes war more likely — even if no one actually wants it. That’s what keeps even experts like Pollack, who are dubious of Trump’s first strike intentions, up at night.

“If you believe that war is imminent, you’re going to want to get your shot in first,” he says. “That is something the North Koreans have promised to do: If we see indications of an attack coming, we’re going to hit you first, and we’re going to use nuclear weapons.”

From North Korea’s point of view, this doctrine makes a grim kind of sense. While North Korea’s military outnumbers that of its South Korean rivals (1.1 million active-duty soldiers compared to 630,000), the South’s forces are better trained and equipped with the latest technology. The North, by contrast, is stuck using knockoff Soviet-era tanks and aircraft. Add in the South’s alliance with the United States, by far the world’s most powerful military, and it’s clear to all observers that North Korea would lose any protracted conflict.

The only hope for North Korea is to anticipate an attack before it happens: to deal a devastating blow to both South Korea and the United States before the fighting really gets going and thus destroy its adversaries’ will to fight. This means that the North Koreans would launch a massive strike — potentially a nuclear one — against South Korea and US military targets if it believed either of these enemies was about to attack.

The North’s most fundamental military doctrine, then, relies almost entirely on reading American and South Korean intentions. Which is why a deliberate policy of making it seem like America is moving toward war with North Korea is so dangerous.

If the policy is working as intended, and the North Koreans really believe America is preparing a first strike, then the North Koreans will start preparing their own.

“If somehow this is actually just a bluff, and an effort to set North Korea on its back foot by convincing it that we’re seriously thinking about military options, it’s nonetheless raising the risk of conflict because North Korea has first-strike incentives,” Rapp-Hooper says.

This makes generally predictable interactions between North Korea and the United States — the kinds of North Korean weapons tests that have already escalated tensions, for example — into much more dangerous affairs.

Typically, the United States responds to North Korean provocations with some kind of show of force: a new military exercise with the South Koreans, an Air Force overflight of the Korean Peninsula, and so on. These are designed to signal resolve, and to show Pyongyang that the Washington-Seoul alliance remains strong.

But if North Korea is already worried about a US attack because of the Trump administration’s threatening behavior, the risks that American signals get misread are higher.

What if North Korea sees an overflight as the first flight in a bombing raid, and shoots down American jets? What if, in the midst of a missile test–induced crisis, Trump or one of his top deputies says something indelicate — something that convinces an already paranoid leader that the US has settled on war?

These scenarios may sound hypothetical, but more North Korean provocations of one sort or another are inevitable. With Trump and Kim in power, each one of them has become a game of Russian roulette.

The more the US prepares for war, the more likely it becomes

For months before the United States invaded Iraq in both 1990 and 2003, the US military engaged in a massive buildup of troops and materiel in the region. North Korea learned a lesson from that: If America suddenly starts ramping up its military presence in your area, war is coming.

“Going as far back as 1994, [the North Koreans] have said that they would not sit there like Iraq did and wait for the United States to build up its forces,” Pollack told me. “They would strike first under those circumstances. And now they’ve said that we’re going to strike you with nuclear weapons, specifically.”

This creates yet another pathway toward war.

The concern here is a kind of cycle of escalation. North Korea does something provocative, Trump says something aggressive in response, North Korea shows it isn’t afraid with another provocation, and the cycle starts again. The more that tensions rise, the more the US military is forced to prepare for the chance that the president might really order them into battle.

Those preparations, most notably the kinds of increased troop deployments to the Korean Peninsula we’ve already been seeing, risk becoming a self-fulfilling prophecy. The North Koreans might read them not as worst-case preparations but as a buildup to a planned invasion à la Iraq. North Korean military doctrine, as far as we can tell publicly, heavily emphasizes strikes on US military positions in the East Asian region.

“Just ramping up — prepositioning troops, stocks, and logistics in a place where we could do it — could prompt the North Koreans to do something,” Sen. Duckworth told me.

It’s important to note here that we also don’t actually understand what red line — what kind of response to a missile test, what kind of military buildup — is likely to set off North Korea. The country is notoriously insular; it’s not clear who actually influences Kim Jong Un or how top decision-makers in Pyongyang assess the risk of war with the US.

There are no direct lines of communication between Trump and Kim, no good way to convey American intentions and reassure the North that war isn’t coming. Sen. Murphy described the US government as “flying blind” when it comes to the North’s intentions.

North Korean defectors, one of the world’s few good sources of information about the Kim regime’s military policy, describe its forces as being on a hair-trigger alert — one where authority to launch an attack is delegated down to individual battlefield commanders who may have little to no understanding of what the US is doing.

“There are tens of thousands of North Korean artillery and short range missiles, ready to fire at any moment,” Thae Yong Ho, a former high-level North Korean diplomat, testified before the House Foreign Affairs Committee in November. “North Korean officers are trained to press the button without further instruction from the general command if something happens on their side.”

With both sides on such high alert and neither capable of being sure about what the other side wants, the chances that a misunderstanding could lead to a catastrophic war are dangerously high.

The public debate in the US does not match this reality

In the runup to the 2003 Iraq War, there was a major public debate in America about the wisdom of the Bush administration’s strategy. It was lopsided, with pro-war voices drowning out antiwar ones, but it was nonetheless the topic in American public life — marked by massive protests and bitter arguments dividing the country’s intellectual class.

A war with North Korea would dwarf the 2003 Iraq War in scope and death toll, yet there is very little in the way of serious public debate happening right now about the risks posed by the Trump administration’s approach — bluff or no.

This is most glaring in Congress, which (per the Constitution) is supposed to make the decision to declare war. In 2003, Bush went to Congress first to ask for authorization to invade. Yet there’s no talk of Trump asking for a similar vote — just an assumption that he could strike whenever he wanted and the rest of the world would have to live with it.

Murphy has proposed a bill that would require congressional approval for a strike on North Korea, but when I asked him if he was getting any support from colleagues on Capitol Hill, his answer was a flat no.

“These are muscles that we haven’t used in decades, having not authorized military action for 14 years,” he said. “It’s hard given how much authority we’ve abdicated to the president over the past decade.”

Beyond Congress, the broader public debate has been far more muted than it was in 2002-’03. There have been no major antiwar demonstrations; public intellectuals seem to assume that war with North Korea is too scary, the possibility of such an awful war too remote, to be worth taking seriously.

Part of that is because, unlike the Bush administration did with the Iraq War, the Trump administration isn’t presenting a united front in favor of war.

There’s no active campaign of trying to sell the American public on a war like there was in 2002-’03, let alone one that relied on the kind of flimsy evidence that Bush’s did. What we’ve gotten instead is a lot of mixed messages from the administration, a lot of signaling that it would be willing to use force (against a country that’s demonstrably more of a threat than Iraq was), without a clear and unmistakable commitment to actually doing it.

On top of that, grassroots energy on the left, the natural leader of an antiwar coalition under a Republican president, has focused on domestic policy, like blocking Obamacare repeal and the travel ban. These issues are demonstrably real, not hypothetical; it makes sense for left-wing activists to prioritize them. But the result is that there’s been little energy left over for a war that doesn’t feel imminent to a lot of people.

So despite the chances of war with North Korea steadily rising, the issue doesn’t have the dominant space in America’s national political dialogue. There’s a chance of conflict on a scale unseen since World War II, a war that could level entire American cities, and it feels like we’re sleepwalking toward it.

Among the small community of experts and policymakers who follow this issue closely, the alarm is palpable. These are the people who most clearly understand what the costs of war with North Korea could be and who most intimately understand the balance of forces on the Korean Peninsula. And they are very, very worried.

“I’ve been out on a window ledge, screaming about this since August,” Rapp-Hooper says. “I think it’s totally scary.”