President Trump’s speech at the United Nations on Tuesday, in which he threatened to “totally destroy” North Korea, provoked an unprecedented response: On Thursday evening, Kim Jong Un delivered a rare televised statement in which he declared, “I will surely and definitely tame the mentally deranged US dotard with fire.” In the Korean version of the statement, he refers to Trump using a phrase that translates as “old beast lunatic” or “old man lunatic.”

Shortly after these comments, North Korea’s foreign minister threatened to test a hydrogen bomb in the atmosphere — something that North Korea has never done, and that no country has done in more than 35 years. On Friday morning, Trump responded to the North’s twin statements with yet another bellicose tweet: “Kim Jong Un of North Korea, who is obviously a madman who doesn't mind starving or killing his people, will be tested like never before!”

Now, this isn’t the first time that Washington and Pyongyang have lobbed insults at each other during the Trump administration — far from it. But North Korea experts say the current round of threats is riskier than previous episodes.

“We've never seen anything like it,” Jenny Town, assistant director of Johns Hopkins University’s US-Korea Institute, says of Kim’s statement. “I would not take this as bluster but would expect action. What action exactly is unclear, but I would expect it to be severe.”

The highly unusual nature of the Kim statement, together with the highly specific nature of the atmospheric nuclear test threat, suggests that the country may really be gearing up to do something provocative. And experts say that as long as Trump insists on handling the North with angry rhetoric like his Friday morning tweet, rather than working to calm tensions, the situation is likely to keep escalating. It’s gotten to the point where the risk of actual war is, according to the Arms Control Association’s Kingston Reif, “unacceptably high.”

“The cycle of the threats and counter-threats has entered an even more dangerous phase,” Reif explains. “We have two volatile leaders with nuclear weapons making it personal and further digging in with their reckless rhetoric.”

What makes this Kim threat different from his previous ones

North Korea makes threats against the US all the time without sparking this kind of reaction from experts. Just a week ago, for example, Pyongyang issued a statement threatening to “annihilate the US imperialist aggressors” and “reduce the US mainland into ashes and darkness,” adding that the US should “be beaten to death with a stick fit for a rabid dog.”

Yet this statement wasn’t greeted with the same level of concern among experts as the North’s Thursday night statements.

There are two reasons for that. The first is the source of the comments. Usually, North Korea’s threats are issued through official press outlets, like the Korean Central News Agency (KCNA) or the Rodong Sinmun newspaper. Kim Jong Un does not personally sign them, and he definitely doesn’t read them on state-run TV. The sheer rarity of a personal statement by the country’s dictator makes the statement a sign that the North is taking the current situation extremely seriously.

“The fact that it is written as if a personal memo from Kim Jong Un to President Trump is unprecedented and worth pause,” Town explains. “It's clear that Kim feels justified in his actions and is insulted at the tone that Trump uses when he speaks of Kim.”

Second, experts say the hydrogen bomb test threat is unique and particularly worrying. Typically, North Korea tests its nuclear weapons in an underground bunker at its Punggye-ri facility. Doing so contains the radioactive fallout and limits the risk of accidentally harming anyone. By contrast, detonating a bomb in the atmosphere over the Pacific Ocean, as the North Korean foreign minister threatened, could spread fallout far and wide.

In 1963, the US and the Soviet Union agreed to cease atmospheric tests because the fallout couldn’t necessarily be contained. The last atmospheric test was conducted by China in 1980. The North conducting one, even far away from populated areas, would be its most serious provocation yet.

“If [Kim Jong Un] did an atmospheric test, that would be a big, big problem,” Mira Rapp-Hooper, a scholar at Yale University Law School who studies North Korea, tells me. “[Any] president would feel compelled to respond in some way.”

These two problems feed each other. Kim’s sense of personal slight could lead him to follow through on the atmospheric test, potentially leading to a response from Trump that brings us even closer to war.

“A personal statement from Kim certainly takes things to a whole new level, and if the North follows through on its apparent threat to test conduct an atmospheric nuclear test, we will be in very dangerous territory,” says Laura Rosenberger, the National Security Council director for Korea and China in the Obama administration.

“This is not a game, and these are not just words,” she adds.

The Trump administration could stop this. Will they?

None of this means that war is likely in the near future. Kim may very well not follow through on his threat to test a hydrogen bomb over the Pacific, and if he does, the American military and political response might well be more restrained than experts fear.

But the fact that we’re even worrying about this suggests that the Trump administration’s emerging strategy to deal with North Korea — fiery rhetoric coupled with a push for harsher economic sanctions — isn’t working very well.

The consensus among North Korea experts is that Pyongyang wants nuclear weapons to deter an American invasion. Threats, like Trump’s vow back in August to respond to North Korean threats against the US with “fire and fury like the world has never seen,” only cause it to feel more insecure. When it feels insecure, it lashes out — demonstrating its own strength in order to signal to Washington that an invasion would be far too costly.

The two sides are essentially caught in a cycle of escalation that could theoretically escalate into outright conflict — even though neither side actually wants a war.

The current situation “is a continuation of the one that started with the ‘fire and fury comments,’” Jeffrey Lewis, an expert on North Korea at the Middlebury Institute of International Studies, tells me.

The threat to test a bomb over the Pacific, specifically, is an example of this cycle in action. It’s the clearest way yet for the North to signal its own strength.

The test “never would have been a consideration for [the North Korean] regime if Trump administration hadn't embarked on a policy of continuous rhetorical escalation,” Barry Pavel, a defense expert at the Atlantic Council, tweeted.

The solution to all of this, the experts say, is very simple: The Trump administration needs to stop unnecessarily antagonizing North Korea and instead start coming up with a strategy for managing the threat it poses.

“It is still a crisis of our own making,” Lewis says. “We can stop it any time by shutting the president up and working to deescalate the situation.”