The United States is now at war with Iran.

This is the inescapable result of President Donald Trump’s order to assassinate Gen. Qassem Soleimani, commander of Iran’s Quds Force, arguably the most powerful military leader in the Middle East, and the most important person in Iran, except for the supreme leader, Ayatollah Ali Khamenei.

You don’t deliberately kill someone like Soleimani unless you’re at war with his country, and even then, you want to think long and hard before you do, given the near-certainty of blowback. The blowback may soon be coming. Friday morning, Khamenei called for three days of national mourning and a “forceful revenge.” It would be shocking if he didn’t follow through.

To convey a sense of Soleimani’s significance, it would be as if, during the Iraq war, the ayatollah had ordered the assassination of Gen. David Petraeus, Gen. Jim Mattis, the head of Special Operations Command, and the chairman of the Joint Chiefs of Staff.* Soleimani’s responsibilities corresponded with all four of these roles. Even then, the analogy falls short because, among Shi’ite Muslims across the region, Soleimani also exuded the charisma of a religious icon, a holy warrior.

For the past 20 years, he had been the architect of Iran’s expansionist foreign policy, running subversive operations and controlling Shiite militias in Iraq, Syria, Lebanon, Gaza, and Afghanistan. In the months after the Sept. 11 attacks, he shared intelligence about al-Qaida and the Taliban with U.S. officials, until President George W. Bush declared Iran to be part of the “axis of evil.” In the fight against ISIS, his militias were crucial in forcing the group’s fighters out of Iraq. But he was also responsible for the deaths of hundreds of U.S. troops during the Iraq insurgency. On Thursday night, the Pentagon justified its action by claiming that he was about to launch an offensive against American embassies and armed forces throughout the region.

Even if that is true, killing him doesn’t make much strategic sense. As important as he was, his loyal and capable lieutenants are still capable of executing the missions. (His deputy, Esmail Ghaani, took formal control of the Quds Force hours after his death.) U.S. officials are already bracing for a variety of counteractions, including embassy stormings (that could make the one in Baghdad this week look like a halfhearted rehearsal), assassinations, cyberattacks, economic sabotage, and military assaults.

It is hard to discern how Trump, who ordered the assassination personally, thinks this will play out. On New Year’s Eve, he told reporters that he wanted peace with Iran. Just two days later, did he think that killing Iran’s top military commander was somehow not an act of war? If he grasped that it was, did he—does he—believe that the blow would bring the regime to its knees or rouse the Iranian people to mount a revolution? (His former national security adviser, John Bolton, expressed that hope shortly after the killing.) Many Iranians, especially in the cities, despise the mullahs in charge of their government, as shown by the massive protests that have swept the country in recent months, but they despise foreign intruders even more. The ghost of Mohammad Mosaddegh, the democratically elected prime minister who was overthrown in a joint American-British coup in 1953, still haunts the Iranian landscape, animating every crisis since.

Trump also said, in his New Year’s Eve comments, that if a war with Iran did erupt, it “would go very quickly.” That is also what Bush’s secretary of defense, Donald Rumsfeld, blithely predicted about the war in Iraq. “Five days or five weeks or five months, but it certainly isn’t going to last any longer than that,” he said a few months before the invasion. It is worth noting that Iran is three times larger than Iraq, with nearly three times the population.

The attack is also certain to alienate the government of Iraq, which would be a necessary ally in a war with Iran. First, the U.S. drone strike took place in Iraq, from the airport in Baghdad, against a motorcade that included Soleimani, who travels freely throughout the region, Second, the attack also killed Abu Mahdi al-Muhandis, head of the Popular Mobilization Forces, a large coalition of Iran-backed militias in Iraq—the point here being that he was an Iraqi, and technically an Iraqi government official. Third, and most crucial, Iraq’s political and military leaders have long tried to pull off a delicate balancing act, catering to their American and Iranian patrons, but in a pinch, they know they can’t afford to alienate the Iranians, their much closer neighbors. And, in this case, after an American attack on Iraqi soil, killing Iraqi citizens as well as one of Iran’s biggest leaders, it will be very hard for them to avoid taking Iran’s side explicitly.

The pro-Iran militias lifted their recent siege on the U.S. Embassy in Baghdad only after Iraqi Prime Minister Adil Abdul-Mahdi agreed to have Parliament hold a debate on whether U.S. troops should be ousted from his country. Even for those many Iraqis who oppose Iranian influence and who may have heaved a sigh of relief at news of Soleimani’s death, it will be hard to defend a continued American presence under the circumstances.

Trump’s actions on Thursday had no strategic purpose.

It might be different if Trump had been responding to a deadly provocation. But this crisis began when a pro-Iran militia fired missiles at a U.S. base, killing one American contractor. No president could have let that deed go unpunished, but Trump’s initial response—five airstrikes on militia-controlled sites in Iraq and Syria, killing 24 people and wounding dozens more—was clearly disproportionate. And his follow-up after the dramatic but bloodless embassy siege, the killing of Soleimani and a few of his comrades, goes well beyond that, constituting a major, in some ways unprecedented, escalation. It will also be observed, by American allies and foes, that none of this would have happened if Trump hadn’t pulled out of the 2015 Iran nuclear deal for utterly capricious reasons.

Trump’s actions on Thursday had no strategic purpose, and this means that, at a moment when he needs allies more than ever, he is less likely than ever to recruit them.

Did Trump have an endgame in mind when he ordered the attack, or was his action, like so many of his words and actions, simply impulsive? Did any of his advisers warn him of the legal implications and the potential political, military, and economic consequences? We now know that Congress wasn’t notified, much less consulted. Did the National Security Council even meet to weigh the pros and cons or to discuss alternative responses? Give Trump’s track record on deliberations, it’s unlikely.

In any case, whether Trump means to provoke a war or wants to pursue a diplomatic course at some point, there is no one around him very capable of doing either. Secretary of State Mike Pompeo has no credibility with Iran, having openly advocated a regime-change policy. Secretary of Defense Mike Esper, a former aerospace lobbyist, has no background in this sort of thing. The policy bureaus in the Pentagon and State Department are desperately short of specialists in the region, most of them having either resigned or been fired. Trump may think this doesn’t matter, having said on many occasions that he knows more about making deals than any general or diplomat—which might be the most worrisome aspect of this crisis.

No one can confidently predict what might happen next. But those who don’t grasp the essence of what happened Thursday night—that Donald Trump declared war on Iran—are kidding themselves.

Correction, Jan. 3, 2020: Due to an editing error, this piece originally identified Jim Mattis as the former head of U.S. Special Operations Command. He was the head of Central Command.