Early yesterday morning, Donald Trump issued a threat on his social media platform Truth Social that would have sounded implausibly extreme if a comic book writer had put it in the speech bubble of a mad scientist or costumed supervillain. “A whole civilization will die tonight,” the president wrote, “never to be brought back again. I don’t want that to happen, but it probably will.”

Taken seriously, this sounded like a threat to use nuclear weapons. At bare minimum, Trump was underlining his earlier pledge to destroy the infrastructure underlying the day-to-day lives of ninety million Iranian civilians by systematically destroying the country’s bridges and power plants. Iran has shown that it retains a considerable supply of missiles and drones, as well as the continued loyalty of allied forces around the region like Hezbollah in Iran and the Houthi government in Yemen. If any version of Trump’s threat had actually been carried out, Iran surely would have done everything in its power to inflict comparable levels of damage on Israel and the Gulf monarchies (which host American military bases). It’s hard to imagine the global economic chaos, never mind the spiraling waves of death and suffering, that would have resulted from anything like this scenario playing out.

As of yesterday afternoon though, it looked like that was exactly what was going to happen. Then Trump backed down. In doing so, he showed something that it’s going to be important to remember next time hawks tell us some new war is going to be an easy victory: even global military and economic juggernauts have their limits.

The ceasefire terms Trump was demanding included major concessions like an end to Iran’s nuclear enrichment program, limitations on even conventional missiles, and ending support for allies like Hezbollah. All of that was a nonstarter from the Iranian perspective. The war had started with the United States and Israel launching a surprise attack while diplomatic talks were ongoing. Iran’s head of state and many other senior officials were assassinated on the very first day. One hundred seventy-five people, most of them young girls, were killed in a strike on the Shajareh Tayyebeh school on the same day. It’s hard to imagine any country in the world agreeing to quickly end a war that had started on such unfavorable terms. Meanwhile, Trump had no interest in pursuing Iran’s starkly opposite ceasefire terms.

Then, as his deadline for ending Iranian “civilization” approached, Trump blinked. He pretended that Iran’s ceasefire terms, which had long been on the table, were a concession he’d extracted with his threat, and he announced a two-week ceasefire while negotiations take place on the basis of Iran’s ten-point proposal. Iran made those points public this morning:

• An American guarantee of nonaggression with Iran.
• Iran maintains control of the Strait of Hormuz.
• Ending the regional war on all fronts, including against Iran’s ally, Hezbollah, in Lebanon.
• Withdrawal of US combat forces from all bases and positions in the region.
• Reparations to Iran for war damages.
• Acceptance of Iran’s right to nuclear enrichment.
• Lifting all primary sanctions on Iran.
• Lifting all secondary sanctions on Iran.
• Termination of all resolutions against Iran by the Board of Governors of the International Atomic Energy Agency.
• Termination of all United Nations Security Council resolutions against Iran.

It’s true that agreeing to negotiate “on the basis” of a proposal is very different from actually accepting any particular point of that proposal. And the White House is already trying to insist that there’s a nonpublic version of the proposal that’s more favorable to US interests. We’ll see. It’s also entirely possible that at the end of the two weeks (or even earlier) things break down and the war resumes as if none of this ever happened.

But as of this moment, even agreeing to anything remotely like this as a “basis for negotiations” is a remarkable development.

Usually, debates about actual or possible US wars around the world proceed on the basis of the assumption that the American empire has the capacity to militarily crush any small nation in the developing world it sets its sights on. Antiwar arguments typically take two forms. Out in the political wilderness, the dissident left argues that the crushing is morally wrong. And in the mainstream, there are pragmatic arguments about “what comes next” post-crushing.

So, for example, many critics of the war in Iran assumed that things would eventually progress to a ground invasion and successful “regime change.” But, they warned, the experience of the occupations of Iraq and Afghanistan show us that being able to crush a country’s military is a very different thing from being able to tamp down on subsequent insurgencies and build up stable pro-American regimes in the wreckage. In failing to crush Iran, though, Trump has reminded us that even globe-spanning empires don’t have unlimited capacity to bend other countries to their wishes.

When the neoconservative writer Jonah Goldberg argued for attacking Iraq in the National Review in 2002, he memorably summarized the views of his friend Michael Ledeen as the Ledeen doctrine. “Every ten years or so,” Goldberg wrote, “the United States needs to pick up some small crappy little country and throw it against the wall, just to show the world we mean business.”

In this case, by picking a country with greater capacity to defend itself than Iraq or Afghanistan (although of course its military strength is a tiny fraction of the United States’), Trump has succeeded in showing the world something very different. Even the vast power of the world’s dominant empire has limits. His initial genocidal bluster was itself downstream of this reality, as was his subsequent capitulation.

If the war had been going better, he would have simply kept doing what he was doing. When it didn’t, he resorted to the most outlandish threats he could think of. When that too failed, he agreed to negotiate on deeply humiliating terms.

Some commentators have suggested that it’s a mistake to talk about Trump chickening out, because this could have the effect of shaming him into recommencing operations. But even aside from the dubious assumption that Trump is likely to listen to anything that antiwar leftists have to say, this misses a deeper point. The debacle in Iran greatly strengthens the antiwar case going forward. Bluntly: one of many reasons not to go around the world starting wars of choice is that sometimes you lose.

Next time hawks try to promote some new American adventure overseas, ask them why they’re so confident that it won’t go like . . . well . . . this.