In Donald Trump’s first term there is a serious possibility of a military conflict, whether intentional or inadvertent, between the United States or Israel and Iran. What follows is how it could unfold, and how it might be avoided.

Step 1: Provocations

Karim Sadjadpour
Karim Sadjadpour is a senior fellow at the Carnegie Endowment for International Peace, where he focuses on Iran and U.S. foreign policy toward the Middle East.
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“It is an undeniable privilege of every man,” wrote the acclaimed American diplomat and scholar George Kennan, “to prove himself right in the thesis that the world is his enemy; for if he reiterates it frequently enough and makes it the background of his conduct he is bound eventually to be right.” Few world leaders embody this ethos more than Donald Trump and Iranian Supreme Leader Ayatollah Ali Khamenei.

For Khamenei and Iran’s hardliners, the United States has been continuously committed to the overthrow of the Islamic Republic of Iran since its very inception in 1979. Everything from U.S. military bases in the Middle East to American celebrity culture is understood as a means to coerce and subvert the Islamic Republic. President Obama’s efforts to allay this paranoia—including numerous personal entreaties to Khamenei—were largely dismissed.

The distrust is mutual. While the 2015 nuclear deal successfully curtailed Iran’s nuclear program, it did little to moderate the country’s longstanding foreign and domestic policies. Internally, civil society arrests have increased and there has been a “staggering surge” in executions. Externally Tehran has continued to arm and finance Syrian dictator Bashar al-Assad, who by one estimate is implicated in the death of over 200,000 civilians (including 45,000 children and women), and the displacement of over 13 million of his citizens. It has also significantly expanded its support for Shiite militias throughout the Middle East which unnerve longtime U.S. allies in Israel and the Persian Gulf.

Even after receiving $1.7 billion in its own frozen assets—at the same time it released U.S. citizens from years in captivity—Iran has continued to take and hold more U.S. citizens hostage. My friend Siamak Namazi and his 80-year old father Baquer, both outspoken advocates of engagement with Iran, have collectively spent nearly three years behind bars on evidence-free charges of espionage.

Since the deal was signed Tehran has violated UN Security Council resolutions (although not the nuclear deal) by reportedly testing at least 12 ballistic missiles, several of which were capable of carrying a nuclear warhead and reaching Israel. Though Iran argues these tests are purely defensive, on at least one occasion the missiles have carried the gratuitously provocative inscription that “Israel must be wiped off the face of the earth.” The U.S. Navy has also recorded over 50 instances of "unsafe and/or unprofessional interactions" by Iran in the Persian Gulf, including the January 2016 capture of American sailors.

While the Obama administration sought to ignore and defuse such tensions with Iran, the Trump administration appears eager to confront them. As National Security Advisor General Michael Flynn simply put it, Iran is “on notice.”

Step 2: Sanctions

One of the fundamental disagreements about the nuclear agreement is whether it is permissible to further sanction Iran for non-nuclear behavior. Washington—including both Democrats and Republicans—says yes, while Tehran believes any additional sanctions constitute a violation. In an August 2015 letter to President Hassan Rouhani, Ayatollah Khamenei warned that “Any imposition of sanctions at any level and under any pretext (including repetitive and fabricated pretexts of terrorism and human rights) … will constitute a violation of the JCPOA and [Iran] would be obligated to take the necessary action … and stop its activities committed under the JCPOA.”

While the nuclear deal allowed for non-American companies and countries to resume commercial relations with Iran, U.S. sanctions largely remained in place. In contrast to the Obama administration, however, which actively encouraged global investment in Iran, the Trump administration has reversed course. Shortly after Flynn put Iran “on notice,” the Trump administration crossed Khamenei’s ostensible red line by imposing additional sanctions against 25 individuals and entities connected to Iran’s Revolutionary Guards (who oversee Iran’s military activities and regional policies). Additional reports suggest the Trump administration may designate the entirety of the Iranian Revolutionary Guards—the country’s most powerful political and economic institution—as a terrorist organization.

While unilateral U.S. sanctions will not be sufficient to moderate Iranian behavior, they are likely to trigger an Iranian response, and a process of escalation.

Step 3: Escalation

The Obama administration was reluctant to vigorously counter Iran’s regional activities for fear of jeopardizing the nuclear deal; the Trump administration has expressed no such concerns. Trump has routinely denounced the deal as a “disaster” and recently began to taunt Tehran on Twitter. “Iran is playing with fire,” he tweeted, “they don't appreciate how ‘kind’ President Obama was to them. Not me!”

Among the few articulated foreign-policy priorities of the Trump administration thus far has been a reset of relations with America’s traditional Middle East allies, namely Israel and Saudi Arabia. Embedded within this is a more confrontational approach toward Iran, which both Tel Aviv and Riyadh believe to be the region’s greatest source of instability. Trump’s national-security brain-trust—including Defense Secretary James Mattis, Flynn, and several of Flynn’s NSC deputies—share this assessment, and hold the Iranian Revolutionary Guards directly responsible for over a thousand U.S. military casualties in Iraq. During the Obama administration they felt restrained, and now they’re eager to show they can and will respond.

The opportunities for confrontation are multifold. The U.S. and Iran are on opposing sides of numerous regional military and political disputes, including in Syria, Yemen, Lebanon, Israel-Palestine, Bahrain, and most recently Afghanistan, where Iran has been accused of becoming “increasingly close” to the Taliban. Despite the U.S.’s overwhelming conventional military superiority over Iran, however, today’s Middle East wars are increasingly unconventional fights involving nonstate actors in weak or failing states where America has no strong allies, unclear interests, and no desire to be. Iran has thrived in filling power vacuums the U.S. military helped create. While the 2003 Iraq war, for example, intended to spread Iraqi democracy to Iran, it instead spread Iranian theocracy to Iraq.

In contrast to the United States, and other democratic countries, the Iranian regime’s foreign-policy adventurism is far less constrained by popular opinion. Countless billions of dollars spent and over a thousand casualties lost in Syria are simply explained away as “fighting terrorism.” While previous U.S. administrations, especially that of George W Bush, tried to appeal to Iranian public opinion by distinguishing between the regime and the people, the Trump administration has ignored such nuance. Trump’s Executive Order attempting to prevent Iranian visa and green-card holders—although no Iranians have been implicated in terror-related deaths in the U.S. since at least 1975—antagonized one of the most pro-American populations in the Middle East.

Days after the Trump administration sanctioned Iran, an Iranian Revolutionary Guard commander warned that “should the enemy make a mistake, our roaring missiles will rain down on them.” Days later a hardline Iranian MP named Mojtaba Zonour boasted that Tehran would respond to Washington’s “slightest aggression” by “razing to the ground” the U.S. military base in Bahrain. And if the U.S. were to fire a missile at Tehran, he said, “Only seven minutes is needed for an Iranian missile to hit Tel Aviv.” After that Trump, not in reaction to Iran but in an attempt to defend himself against charges of being a lackey for Russia, tweeted that Iran was “#1 in terror.”

Over the last four decades the U.S. and Iran have regularly engaged in rhetorical, maritime, aerial, and proxy battles. More recently this cold war has also moved to cyberspace. Yet such brinksmanship, while at times close, has never deteriorated into a full-blown conflict. Given the confluence of explosive issues and explosive personalities, however, this time may be different.

Step 4: Unraveling

In Ernest Hemingway’s The Sun Also Rises, a Scottish war veteran named Mike Campbell is asked how he went bankrupt. “Two ways,” Mike said. “Gradually and then suddenly.” Similarly, a U.S.-Iran escalation could potentially build for years before the nuclear deal collapses. Though politicians on both sides routinely denounce the nuclear deal, it remains unclear whether they would truly welcome the deal’s collapse. Neither the U.S. nor Iran will want to be blamed for unilaterally tearing up the agreement and potentially triggering a global crisis. A more likely scenario is one in which the deal gradually unravels, with each side blaming the other for its demise.

Iran’s supreme leader signed the deal under economic duress but never offered a strong endorsement of it, nor gave the impression he is firmly committed to the deal’s 10-year duration. On the contrary Khamenei regularly complains about its unmet economic expectations, blaming the “devilish” United States for scaring away foreign business while at the same time regularly denouncing foreign investment as a Trojan horse for Western imperialism. In a meeting with a group of Iranian poets he suggested they write “to-the-point poetry ... expressing the Americans’ instances of treason in the issue of JCPOA” in order to sour popular views about the deal.

In an atmosphere of increased escalation, sanctions, and regional skirmishes, Iran’s hardliners will find ample pretexts to make good on their threat of reexamining their nuclear commitments. But rather than race toward a nuclear weapon, which would provoke a strong international reaction, Tehran is more likely to reduce cooperation with international inspectors and resume its nuclear activities—under the pretext of a civilian energy program—in a way that will accentuate fissures in the international coalition (known as the P5+1) that negotiated and enforces the nuclear deal.

I asked my Carnegie colleague Mark Hibbs—a renowned nuclear researcher—how, specifically, Tehran might go about this. “If Tehran aimed to divide the P5+1 and aggravate Israel and Western countries,” Hibbs told me, “it might do things not expressly forbidden by the JCPOA but that would not be in the spirit of the accord. Iran's scientists might do theoretical studies suggesting they are interested in nuclear weapons, enriching uranium with lasers, and plutonium metallurgy; Iran's diplomats might get suddenly tougher in negotiations with the IAEA over access to places inspectors want to visit.”

In essence Tehran will likely move deliberately enough to split the P5+1 coalition—the U.S., China, Russia, France, Germany, and the U.K.—between those who argue Iran must be further penalized for violating the nuclear agreement (Washington) and those (Beijing, Moscow, and most of Europe) eager to preserve the deal who argue more diplomacy, not pressure, is needed.

Step 5: Disunity

The JCPOA builds in dispute-resolution mechanisms in case either Iran or the P5+1 countries feel the other side is in non-compliance. But any such mechanism is ineffectual when two parties are seemingly coveting an escalation. And any U.S.-Iran escalation may break the unity of the U.S. and its partners.

Given the chaos and carnage in today’s Middle East, most major countries in the world (with the notable exception of the U.S., Israel, and Saudi Arabia) see Iran as a stable regional power and a tactical ally against the more nefarious threat of radical Sunni jihadists like ISIS. Russia is working in unison with Iran in Syria, Chinese-Iranian trade is booming, and Europe cannot afford another unpredictable conflict that exacerbates regional unrest and creates more refugees.

Despite Trump’s curious affinity for Vladimir Putin, rather than side with Washington in a U.S.-Iran dispute it is more likely that Putin will simply continue to play the U.S. and Iran off each other: supporting sanctions and pressure that make Iran more isolated and dependent on Moscow, while telling Tehran it has diluted Washington’s attempt to meaningfully sanction and pressure them.

The Obama administration’s greatest ally in isolating Tehran, ironically, was the previous Iranian President Mahmoud Ahmadinejad, whose bombast and holocaust denial convinced many countries around the world that the problem was Tehran, not Washington. In contrast, today much of the world perceives Iran to have a reasonable president in Hassan Rouhani—who is up for reelection in May 2017—and an urbane Foreign Minister in Javad Zarif, while Trump is perceived as America’s Ahmadinejad.

History has shown that Iran only responds to pressure when it is encircled with a united international front. Unilateral U.S. pressure, however significant, is insufficient if Tehran feels it has escape doors in Europe, Russia, and Asia.

Step 6: Conflict

A context in which Iran has resumed its nuclear activities and a divided P5+1 fails to meaningfully react creates a dilemma for both the United States and Israel. Israeli Prime Minister Benyamin Netanyahu—who views Iran an “existential threat”—has a lower threshold than the United States for taking military action against Iran. While the Obama administration restrained Netanyahu, Trump has thus far indulged him. Though Netanyahu may not succeed in compelling Washington to strike Iran’s nuclear facilities—his first preference—he may succeed in getting Trump’s greenlight, and the requisite military hardware, for Israel to take military action.

What is the likelihood that Trump himself would authorize military action against Iran’s nuclear sites or military assets? One of Trump’s core beliefs, taught to him by his former lawyer Roy Cohn, is “When attacked, hit back harder.” While it remains to be seen how a philosophy born out of New York City real estate quarrels can be applied to complicated geopolitical disputes, throughout his campaign and his first weeks in office Trump’s decision making has been marked by impulsiveness more than restraint. How will he react if Iran continues to defy him despite his repeated taunts and tweets?

Trump’s confrontational style is coupled with a core national-security team that is universally cynical about Iran. Flynn, Vice President Mike Pence, CIA Director Mike Pompeo, and likely Deputy Secretary of State Elliott Abrams were all outspoken opponents of the nuclear deal. Last fall Abrams advocated “sinking an Iranian ship” to show resolve. While Mattis has not recommended scrapping the nuclear deal, he has called Iran “the single most enduring threat to stability and peace in the Middle East.”

In addition to concerns that Trump’s social-media outbursts may cause an inadvertent conflict, serious observers also worry that Trump could use either a terrorist attack or an external conflict—preferably with a longstanding Islamist adversary—to expand his power. Trump’s strategic advisor Steve Bannon said in November 2015 that Islam was “the most radical” religion in the world and “we’re clearly going into … a major shooting war in the Middle East again.”

To those looking for “shooting wars” in the Middle East, Iran provides an unparalleled opportunity. On numerous occasions over the past two years the U.S. Navy has fired warning shots against Iranian Revolutionary Guard patrol boats in the Persian Gulf and interdicted shipments of weapons bound for Yemen’s Houthis, whose recent attack on a Saudi ship was allegedly intended for the United States. In essence the opportunities for conflict with Iran are numerous and interrelated: An unraveling of the nuclear deal could trigger a regional war, or a regional war could trigger an unraveling of the nuclear deal.

Step 7: Repercussions

In one of his final interviews before dying at age 101, Kennan reflected that "Anyone who has ever studied the history of American diplomacy, especially military diplomacy, knows that you might start in a war with certain things on your mind as a purpose of what you are doing, but in the end you found yourself fighting for entirely different things that you had never thought of before. War has a momentum of its own, and it carries you away from all thoughtful intentions when you get into it. … War seldom ever leads to good results."

The chain-reaction of even “targeted” military strikes on Iran’s nuclear facilities would be unpredictable, enormous, and long-lasting. Hundreds of articles have been written over the last decade assessing its potential impact. Among its many retaliatory options Iran has the power to either attack, or potentially activate sleeper cells in, the oil-rich, predominantly Shia eastern province of Saudi Arabia, sending energy prices skyrocketing. Iran may also feel unrestrained attacking U.S. forces in the region, (mis)calculating that Trump is unlikely to respond given the American public’s fatigue with wars in the Middle East.

In addition to potentially triggering a global economic crisis and pouring gasoline on a region already in flames, military action against Iran would likely further entrench the most hardline elements of the Iranian Revolutionary Guards for years to come, revitalize their moribund revolutionary ideology, and compel them to pursue deterrent nuclear weapons in earnest. That possibility could turn what began as targeted, limited strikes into a full-blown regional war.

What is to be done?

The last four decades of U.S. policy toward Iran shows Washington’s limited ability to change the nature or behavior of the Iranian regime. The George W. Bush administration tried harder than any U.S. administration to intimidate Iran militarily and support Iranian democracy activists, yet during his time in office Iran relentlessly attacked U.S. forces in Iraq and the country’s reform movement withered. The Obama administration tried harder than any U.S. administration to improve relations with Tehran, including numerous letters Obama wrote to Ayatollah Khamenei, yet Iran’s hostility toward the United States and its longtime regional policies remained unchanged.

Among the important lessons of the 2015 nuclear deal is that two policies often thought of as opposites—coercion and engagement—are in fact complementary. In private conversation Obama’s senior aides note he was eager to seriously negotiate a nuclear deal with Iran from the very beginning of his presidency, but it was not until Tehran was faced with a global economic embargo that it began to seriously engage. In the aftermath of the nuclear deal, the Obama administration only employed one aspect of this formula—engagement—to try to compel Iran to reconsider its longtime regional policies. In contrast to the enormous costs Tehran endured for its nuclear intransigence, it has paid little penalty for being the chief accomplice to a Syrian regime responsible for one of the greatest humanitarian crises in modern history.

While the Trump administration seeks to counter Iran’s regional policies, its strategy is missing two essential ingredients: multilateralism and U.S. engagement. Nearly all Iranian economic trade is with countries other than the United States. For pressure to work it is essential that Washington closely coordinate with Iran’s largest economic and strategic partners, namely China, Russia, Europe, India, and South Korea. Trump’s derisiveness toward U.S. allies and denunciations of a nuclear deal most of the world deems necessary for global stability will make it difficult to compel these countries to forsake their own commercial and strategic interests with Iran to please Washington.

The most successful playbook from which Donald Trump can borrow remains the one America used in several decades of containing, countering, and ultimately defeating the Soviet Union. George Kennan, the original author of that policy, advised in his seminal long-telegram from Moscow that “the main element of any United States policy … must be that of long-term, patient but firm and vigilant containment … designed to confront the Russians with unalterable counterforce at every point where they show signs of encroaching upon the interests of a peaceful and stable world.”

Yet given Trump’s ambitious inaugural promise to “eradicate radical Islamic terrorism completely from the face of the Earth,” a policy whose success is measured in years if not decades will appear weak and inadequate. This lack of strategic patience is precisely why the prospects for conflict with Iran are greater than they’ve ever been.

This article was originally published by the Atlantic