President Trump has cancelled his highly anticipated June 12 summit in Singapore with North Korean leader Kim Jong-un via a letter released by the White House Thursday:

Trump cancels on Singapore meeting via letter to Kim pic.twitter.com/PBgcijjEgE — Jennifer Epstein (@jeneps) May 24, 2018

It’s possible that this is all a negotiating tactic and that the two sides will come back together again soon, but the tone of the rhetoric coming from Washington and Pyongyang lately makes that seem unlikely.

The administration could not have set expectations for this meeting higher, with the president boasting about deserving the Nobel Peace Prize and the White House issuing a widely ridiculed commemorative coin for the summit referring to Kim as the “supreme leader.” Trump’s opponents might be tempted to crow about this, but the fact is that the world is significantly more dangerous when Kim and Trump are lobbing threats at each other than it is when they are talking.

This is also a major setback for the government of South Korea—the country with the most to lose from conflict between the U.S. and the North—which had pushed hard for the summit and, just a few days ago, described it as a “99.9 percent done deal.” If it’s a victory for anyone, it’s national security adviser John Bolton, who before taking this job had advocated for preventive military action against North Korea and who never seemed on board with the idea of talking to Kim. It was Bolton, arguably, who set this slow motion disaster rolling.

Trump first accepted Kim’s invitation to meet, delivered via South Korea’s government, back in March. The date and location were selected two weeks ago. But even as the anticipation has been building, there’s been an escalating war of words between the two sides that has now derailed the whole process.

But the seeds of the summit’s destruction had already been planted on April 29 when Bolton told CBS News that he envisioned North Korea following the “Libya model” of disarmament, meaning that it would give up its weapons all at once and permit inspections, rather than a gradual drawn-down process of mutual concessions by each side.

On May 15, a North Korean official issued a statement rejecting the idea of immediate disarmament and objecting specifically to Bolton’s “Libya” comment—the North Koreans, as Bolton no doubt knew, see the fate of Muammar Qaddafi’s government as a lesson in why not to give up your weapons of mass destruction.

On May 17, Trump was asked by the press about the “Libya model” issue in the Oval Office, and completely misinterpreted it, seeming to think that Bolton was referring not to the 2003 agreement under which Qaddafi gave up his weapons, but to the 2011 intervention that led to his overthrow and death. This turned an implicit threat into an explicit one.

Then on Monday, Vice President Mike Pence, in what seemed to be an attempt to clean up his boss’s mess, turned Trump’s misreading of the Libya model into official policy, telling Fox News, this will only end like the Libyan model ended if Kim Jong-un doesn’t make a deal.” When told that could be interpreted as a threat, he replied, “Well, I think it’s more of a fact.”

On Wednesday, an aide to Kim Jong-un released a statement calling Pence a “political dummy” for his remarks and saying, “Whether the U.S. will meet us at a meeting room or encounter us at nuclear-to-nuclear showdown is entirely dependent upon the decision … of the U.S.”

Trump’s letter today said that the “tremendous anger and open hostility” in that statement made holding the summit “inappropriate.” For good measure, Trump added, “You talk about your nuclear capabilities, but ours are so massive and powerful that I pray to God they will never have to be used.”

After weeks of chumminess, we appear to be back to “fire and fury.”

It’s possible that the summit was always doomed, given the fact that the two sides have very different ideas about what “denuclearization” means. And reports that Trump, despite expecting an instant breakthrough on denuclearization, was preparing little for the high stakes meeting, simply believing that “In the end it will work out” did not inspire confidence. It’s also likely North Korea never intended to give up its long-sought nuclear deterrent at all. But talks between the two sides, no matter how drawn out and inconclusive, could have at the very least ratcheted down military tensions on the peninsula. The diplomacy had already borne some fruit, in the release of three American prisoners this month. The collapse of talks only makes a catastrophic conflict more likely—and we’re back to wondering which country the U.S. will fall into a war with first.