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The U.S. airstrike that killed Qassem Soleimani, head of Iran's Revolutionary Guard Quds Force, and Abu Mahdi al-Muhandis, a leader of Iranian-backed militias in Iraq, was not simply a sharp departure in the Trump administration's policy toward Tehran. It also marks a larger shift in America's response to Iranian influence and provocations in the Middle East.

President Donald Trump has gambled that an extraordinary escalation will reassert control of an intensifying U.S.-Iran confrontation. It may actually work. But weathering the diplomatic and military fallout will require far greater skill than Trump's team has displayed so far.

The political scientist Robert Jervis once distinguished between the "spiral model" and the "deterrence model" of conflict. In the spiral model, hitting an opponent simply causes him to hit you back; escalation begets escalation. In the deterrence model, hitting an opponent hard enough leads him to back down; a sufficient show of strength can beget de-escalation.

For much of the past two decades, the U.S. has mostly followed the logic of the spiral model in dealing with Iran. Iranian forces and Iraqi proxies under Soleimani's command used improvised explosive devices to kill hundreds of American troops following the U.S. invasion of Iraq in 2003. Yet the George W. Bush administration — while periodically confronting Iraqi Shiite radicals under Iranian influence — mostly refrained from targeting top Iranian operatives such as Soleimani, for fear of provoking escalation with Tehran and a political backlash within Iraq.

The Barack Obama administration also found the logic of the spiral model compelling. Obama never doubted that the U.S. had greater power than rivals. But he worried that Iran and other competitors had a greater intensity of interests within their home regions, and believed that confrontational policies might simply induce confrontational responses.

In dealing with Iran, then, that administration brought great economic, diplomatic and other pressures to bear in hopes of securing a nuclear accord. Yet Obama showed restraint when it came to military or paramilitary confrontations with Iran and its proxies, whether in Iraq, Syria or elsewhere. (The administration did respond militarily, late in Obama's presidency, to attacks by Iranian-backed Houthi rebels on shipping at the entrance to the Red Sea, but in a deliberately restrained way.)

Trump's approach was initially harder to categorize. In some ways, he pursued a policy of maximum antagonism, by pulling out of the nuclear deal Tehran negotiated with the West in 2015 and imposing harsh economic sanctions. But after attacks on oil tankers, Saudi oil facilities and a U.S. drone, all of which the U.S. blamed on Iran, Trump repeatedly held back from any overt military response.

This latest escalation represents an implicit admission that Trump's earlier strategy failed — that economic antagonism plus military restraint had provoked Iran but not adequately deterred it. That failure was confirmed most recently by militia attacks on U.S. facilities and personnel in Iraq, and by the menacing New Year's Eve siege of the U.S. embassy in Baghdad. Meanwhile, Trump's disordered policy had sown doubt among U.S. partners in the Persian Gulf and throughout the region, who worried that Washington might not defend them from Iranian attacks that American policy was helping to incite.

Confronted with this failure, and also with evidence that Soleimani was apparently plotting additional attacks, Trump took several steps up the escalatory ladder. U.S. forces did not simply seek to disrupt attacks in preparation, or respond proportionately to them. They killed two of the most important men in Iran's network of influence in the Middle East. Soleimani, in particular, was Iran's "indispensable man" in countries from Lebanon to Yemen; he was the very symbol of Tehran's strategic reach in the region and its defiance of the U.S. and other enemies.

The calculation here seems to represent a shift from the spiral model to the deterrence model. By raising the stakes sharply, the thinking goes, Washington can shock Tehran and demonstrate how much the Iranian regime has to lose through further provocations. If Obama worried that Iran's asymmetry of interests would outweigh America's asymmetry of power, Trump is now calculating that America's asymmetry of power — its ability to inflict far worse suffering on Iran's regime than it can inflict on the U.S. — will outweigh Tehran's asymmetrically intense interests in the region.

To call this a gamble is an understatement. Soleimani may have been a loathsome terrorist in American eyes, but he remains a national hero in Iran, and there will be immense pressure for some sort of retaliation. Iranian forces and proxies are capable of attacking — either immediately or over the long-run — U.S. military assets, diplomatic facilities and citizens in Iraq and throughout the Middle East. Tehran could also respond with cyberattacks, further assaults on Gulf oil infrastructure or proxy attacks against Israel. Tehran could further cast off the remaining restraints on its nuclear program; it could, and probably will, use its influence with Iraqi politicians in a bid to evict U.S. forces from Iraq. There are plenty of ways in which a U.S. operational success could turn into a strategic setback or a deeper confrontation.

That said, Trump's wager may pay off. The Iranian regime has historically been aggressive but not suicidal. The knowledge that the U.S. can and will target top regime leaders probably terrifies Iranian officials as much as it enrages them. And whereas Iran had been controlling the pace of the confrontation before this point — gradually increasing the military pressure in response to U.S. economic pressure — Washington has now shown its ability to escalate in unexpected and devastating ways.

Right now it is Iranian leaders who surely feel that they have badly misjudged the enemy. That realization may indeed have a sobering effect as Tehran considers whether it would profit from intensifying the confrontation.

One thing is certain: Navigating the current crisis will require a higher quality of statecraft than has been the Trump administration's norm. The U.S. will need to protect or evacuate vulnerable personnel and private citizens in Iraq and elsewhere in the region. It must formulate contingency plans for handling potential Iranian response. It must simultaneously maneuver so that this strike doesn't isolate America in the international diplomacy surrounding the Iran nuclear issue, and determine how it will respond when Tehran uses its political sway in Iraq to push for a U.S. withdrawal.

The administration's showing to date is not reassuring. Trump has generally sundered, neglected or undermined diplomatic relationships within the region and beyond that would be valuable right now. Tight messaging and skillful execution of policy have not been hallmarks of his presidency. Former secretaries of state such as Dean Acheson and George Shultz would have their hands full in dealing with this crisis, and nobody in Washington right now looks like another Acheson or Shultz.

"The game has changed," Secretary of Defense Mark Esper warned hours before the strike. True enough. We'll see if the Trump administration is ready for what comes next.

Hal Brands is a Bloomberg Opinion columnist, the Henry Kissinger Distinguished Professor at Johns Hopkins University's School of Advanced International Studies, and a scholar at the American Enterprise Institute. Most recently, he is the co-author of "The Lessons of Tragedy: Statecraft and World Order."