For those who warned Donald Trump not to jettison the Iran nuclear deal struck by his predecessor, the spasm of violence that erupted Wednesday night likely confirmed some of their worst fears. “I assume the gloves are off for the Iranians,” Ian Bremmer, the founder and president of the Eurasia Group told me on Tuesday, shortly after the president had announced that he would be withdrawing the United States from the international agreement and reinstating severe economic sanctions on Tehran. “It makes mutual military escalation between the Israelis and the Iranians much more likely.” Less than 48 hours later, Israeli warplanes were pummeling dozens of Iranian military targets in Syria, in retaliation for what the Israeli military described as a failed rocket attack on the Golan Heights. “If there is rain on our side, there will be a flood on their side,” Israel’s defense minister said, claiming that nearly all of Iran’s fortifications in Syria had been destroyed overnight Wednesday. “I hope we have finished with this round and that everybody understood.”

The exchange of fire was predictable: for months, Israeli and Iranian forces have been trading blows in Syria. Prime Minister Benjamin Netanyahu of Israel had been a fervent advocate for scrapping the Iran deal, personally lobbying President Trump to tear it up, and has not been coy about his desire for more aggressive military action. The overnight missile strike was merely the most visible expression of a long-simmering proxy war.

It may also have been entirely preventable. As the Associated Press reported Thursday, European leaders had agreed “in principle” to a new deal that would address Trump’s toughest criticisms. Since January, Trump had been warning his European partners to the agreement—including Britain, France, and Germany—that he would scupper the arrangement if they didn’t present a “fix” to the Joint Comprehensive Plan of Action, the official title of the Obama-era agreement. The Europeans, apparently, relented. Trump reportedly tossed a grenade into the negotiations and walked away anyway.

Administration insiders were always skeptical that Trump would accept a supplemental deal, given his unyielding contempt for his predecessor’s accomplishment. “This was absolutely an inevitability. The president has been wanting to pull out of this deal since the campaign,” a current administration official told me earlier this week. “The last time he re-certified, the president made clear that he would not do so again.” Attempts by European leaders to change his mind were futile: according to the A.P., U.S. allies in Europe signaled that they were willing to penalize Iran’s ballistic missile program and expand access for U.N. nuclear inspectors—two of Trump’s chief demands. Negotiations were also ongoing to maintain the restrictions on Iran’s enrichment of uranium indefinitely.

Of course, fixing the deal was not Trump’s intent. On Tuesday, he declared that the J.C.P.O.A. was a “horrible, one-sided deal” that “didn’t bring peace, and it never will.” For Trump, pulling out of the deal delivers on a campaign promise and could serve him well in domestic politics. But diplomats and foreign-policy experts I spoke with fear that Trump may have irreparably damaged the transatlantic partnership. “Trump may have aimed at the Iranians, but he’s hit the Europeans,” one former senior U.S. official told me. “It’s not only a challenge to the substance of what was agreed along with the French, Germans, and British—not to mention the Russians and the Chinese—but in addition, it’s a challenge to the way they work: they seek carefully crafted, multilateral agreements through painstaking negotiations. We’ll see if that repudiation of form, as well as content, has repercussions elsewhere.”

The path forward remains murky. “There is no there there when it comes to a substitute or follow-on,” a current State Department staffer told me. “What is the alternative that is so great?”

For now, Europe and Iran are telegraphing that they remain committed to the J.C.P.O.A. But whether the agreement is sustainable without the United States—which will snap back the nuclear-related sanctions waived under the Iran deal over the next three to six months—remains an open question. Meanwhile, Trump and his hawkish national security adviser, John Bolton, say the administration will continue to work with the agreement’s primary signatories, China and Russia among them. Still, the feeling in the international community is bleak. “I do not expect many results, because Europe can’t take Washington seriously [anymore],” a foreign diplomat told me Thursday morning, adding that the U.S. is losing credibility on the world stage. “You can’t just pull out of an international treaty every time you change a president. Diplomacy does not work like that and this makes the world a less safe place.”