Is Iran about to unleash a wave of terrorism against the United States?

In explaining his decision to oppose the nuclear deal with Iran, Sen. Chuck Schumer (D-NY) declared that what concerns him most is that “Iran would receive at least $50 billion dollars in the near future and would undoubtedly use some of that money to redouble its efforts to create even more trouble in the Middle East, and, perhaps, beyond.” In focusing on the money Iran will gain from sanctions relief — and predicting a deluge of terror if the pact goes through — Schumer is jumping on one of Washington’s most crowded bandwagons.

Just last week, David Brooks warned in his New York Times column that “Iran will use its $150 billion windfall to spread terror around the region,” echoing numerous U.S. legislators who were themselves echoing former CIA director Mike Hayden’s comment, “that an absolutely inevitable byproduct of the deal would be to strengthen the Iranians in doing all these other things that are causing us such great grief throughout the Middle East and Persian Gulf.” Sen. Mark Kirk (R-IL), expressed his concerns to the Daily Beast: “if under a final deal, as reports are indicating, the Iranian regime gets as much as $150 billion back [in] sanctions relief payments, even more money will be freed up for Iran to export aggression and support terrorists targeting the United States, Israel and other allies.” Even Texas Republican Sen. Ted Cruz’s loopy claim that Barack Obama’s administration “will become the world’s leading state sponsor and financier of radical Islamic terrorism” still reverberates.

Indeed, this claim that that nuclear pact will result in a record-setting spate of terrorist attacks has been leveled so frequently and countered so poorly by the White House — which seems locked into talking points that focus solely on the agreement’s value on the nuclear front — that it has become Beltway gospel.

But the issue, and its effect on the debate about the nuclear agreement, is too important to leave in the realm of political rhetoric. Iran is indeed the world’s foremost state sponsor of terrorism, and by a large margin. Tehran-backed operatives have been arrested on terrorism charges in recent years in such disparate places as Kenya, India, Azerbaijan, and Cyprus. American allies in the Middle East, from Israel to the Gulf monarchies, have well-founded fears of Iranian terrorism and subversion; deal or no deal, Washington will need to continue showing vigilance against Iranian plots to reassure them. Still, the proposition that sanctions relief — which the administration says will yield Iran less than $60 billion and opponents claim will deposit as much as $150 billion in Tehran’s coffers — will prompt Iran to let loose a huge new wave of terror still deserves some serious analysis.

The first question is whether a stepped-up campaign of terror is a plausible course for Tehran, should the deal go through. Yes, Iran is already doling out plenty of money to support the Bashar al-Assad regime in Syria and Hezbollah’s efforts to defend it, as well as to the Houthis in Yemen and Shiite militias in Iraq. We should not expect Iran to decrease that activity: Tehran has made clear that these are key priorities — and it seems a good bet that some of the money it will recover from sanctions relief will be devoted to these and other unwelcome efforts. Moreover, after disappointing hardliners by entering into the agreement with P5+1, Supreme Leader Ayatollah Khameini may want to compensate them for the setback.

Mike Hayden’s former agency, the CIA, apparently does not believe that most of the money will be used to support extremists, according to reporting about a classified briefing in Congress published last month in the Los Angeles Times but that is clearly a minority view.

Does it follow that the Iranians would devote the money to terror attacks, specifically against the United States? Would Iran really want to endanger the nuclear deal?

Well, if that’s the case, Tehran would have to bet that it could carry out attacks that the United States would not be able to attribute to it, or that the nuclear deal would be so important to officials in Washington that they would tolerate some amount of terrorist violence to preserve it. The latter doesn’t pass the straight-face test, and as to the former: for most of the past 20 years, the Iranians have shown a healthy respect for the capabilities of U.S. intelligence and law enforcement to get to the bottom of any attack quickly.

For Tehran, recognition of that fact came after the 1996 Khobar Towers bombing in Saudi Arabia, which killed 19 U.S. airmen. The attack has been attributed to Saudi Hezbollah, a group supported and directed by Iran and its Lebanese proxy Hezbollah specifically for the operation. The goal, so far as we can tell, was to get the United States to withdraw its forces from the Arabian Peninsula.

Appalling as the bombing was — it employed the largest truck bomb ever seen at that time, and most of the victims were cut to ribbons by flying glass — the aftermath was telling: The United States soon developed leads indicating that Iran was behind the attack. Investigators’ efforts to solidify the attribution, however, were frustrated by Saudi Arabia’s refusal to hand over evidence and witnesses, fearing that a U.S. retaliation would have destabilizing consequences. Iran escaped a military reprisal but, after Khobar, anyone who attacked the United States could not bank on evading detection. In short, the Iranians have since been deterred from carrying out terrorist attacks directly against the United States — even if it has not shied away from supporting others who were attacking American troops on the battlefield, such as Shiite militias in Iraq and the Taliban in Afghanistan.

Khobar was thus the culmination of a period when state-sponsored attacks were the principle form of terrorism the United States faced. That era began in the 1980s with the Hezbollah bombings of the U.S. embassy and the Marine barracks in Beirut, and the many kidnappings and killings that group and other proxies carried out around the world. Since the 1996 attack, a small number of Americans have been caught up and killed in Iranian-backed terror attacks directed against Israelis, but specifically American targets have not been struck.

The only Iranian plot in recent years that would have caused American deaths if it been carried out was one of the strangest in terrorism history. In 2011, an Iranian-American used-car salesman named Manssor Arbabsiar was arrested for trying to arrange for a Mexican drug cartel to assassinate the Saudi ambassador in Washington. The plan was to bomb a D.C. restaurant, where presumably plenty of Americans would be dining, and the conspiracy was authorized by the Iranian Revolutionary Guards Corps.

The plot turned out to be low comedy, more Seth Rogen and The Interview than some suave, technowizard Bond villain: to carry out the assassination, the car salesman approached a narco-trafficker who happened to be a U.S. informant. Indeed, counterterrorism officials are still scratching their heads about the fact that the Iranians could have greenlighted something so manifestly goofy. So, another lesson: The Iranians aren’t all 10 feet tall.

The Arbabsiar plot is instructive because it came during 2011-2012 when the threat of a renewed wave of terrorism was probably greatest because the nuclear stalemate looked liked it might lead to military action. During that time, several Iranian and Hezbollah plots were disrupted (the key ones were in Cyprus and Thailand), and Hezbollah bombed a bus at the airport in Burgas, Bulgaria, killing five Israeli tourists and their driver.

As demonstrations of Iranian intentions, those events were invaluable to the United States, which began a renewed and ultimately successful push to get the European Union to finally ban Hezbollah’s military wing. No genuinely spectacular plots emerged; the combination of intelligence successes against Iranian terrorists and the initiation of serious negotiations seems to have convinced Tehran to desist — another demonstration that the United States can handle Iranian malfeasance in this area.

Whether the plots are inept or not, there is no excusing the Islamic Republic’s guilt. But in gauging the potential threat of a revived campaign of Iranian terror, it’s worth remembering that state-sponsored terrorism of the kind Iran has practiced is not the catastrophic terrorism of al Qaeda and its jihadi followers. Instead of seeking to kill on the grand scale, Iran’s terrorist attacks have always been smaller and carefully calibrated so that its enemies would not use these attacks as justification for military reprisal or retributive war. It has typically sought deniability, which is at least in part also a function of scale. There is a reason administrations of both parties did not consider terrorism a top-tier issue until 9/11, when actors like al Qaeda, which had no state sponsors to restrain them, shifted the paradigm of modern terrorism.

Another line of argument about a future Iranian terrorist threat has been put forward by Sen. Tom Cotton (R-AR) and Rep. Ron DeSantis (R-FL), who have observed that Iranian-backed Shiite militias such as Kataib Hezbollah and Asaib Ahl al-Haq killed as many as 1,500 American troops during our eight-year military mission in Iraq. Both men are veterans of the war in Iraq and write with understandable emotion in a Time magazine article last month: “When we remember those fallen comrades as well as those who lost their lives in Iran-sponsored terrorist attacks it is difficult to believe we would enter into a deal with a regime that supports such behavior.” The two also express certainty that “the Iranian regime will plow a portion — if not all — of the monetary windfall it receives from the deal into terrorism. That terrorism is likely to be targeted at the United States and our allies.”

The legislators write carefully, distinguishing between American forces killed by Shiite militias in Iraq and others killed by terrorism, but the distinction being made is likely lost on many readers. There is, notoriously, no single definition of terrorism — even in the many relevant pieces of U.S. legislation. In contrast with the Khobar Towers case, in which the troops killed were not on a combat mission, attacks against troops in a combat zone are not considered “terrorism.” Unless we are contemplating another long-term, large-scale stay in Iran’s neighborhood, the Cotton-DeSantis argument cannot be taken to prove the inevitability of anti-American terrorism. Rather, it only reminds us of the obvious: We negotiated a nuclear deal with a deeply hostile country.

Yes, Iran will use its fresh cash for unwelcome purposes. It will likely spend considerable sums on its effort to shore up the Assad regime, which is bad news for those who want to see that murderous dictator gone — though perhaps not such bad news for those who worry about the Islamic State taking over the country. Tehran will also give an acutely needed financial transfusion to Hezbollah, which is strained by its engagement in Syria and weakened at home in Lebanon. Israel, which has suffered the most at the hands of Iranian-backed terror, has the best justification for being concerned about arms and weapons making it to Hezbollah. The United States must continue to help the Israelis strengthen their defenses, and, in that respect, the American-funded Iron Dome antimissile system has already provided a dramatic new and reliable defense against Hezbollah rocket attacks. Hezbollah isn’t going away anytime soon. But with the Lebanese group heavily focused on Syria, the growing threat in the neighborhood comes more from jihadis like the al-Nusra Front and the Islamic State than any other source.

Iran will also likely pump money and arms to the Houthis in Yemen, the Shiite militias in Iraq, and others proxies who are on the frontlines of the runaway sectarian conflict in the region. That will cause great anxiety in Saudi Arabia and the Gulf monarchies, but these states have shown that they can up the ante with Iran any day, as they are right now in Yemen, with a UAE brigade now in action there, complementing Saudi Arabia’s air campaign. (It may be worth noting the limited regard some of our Gulf friends show for American concerns about terrorism. It was telling indeed, that the newly ascended Saudi King Salman could not make it to Camp David for a planned summit for President Obama but recently had time to meet a delegation from Hamas, which the Saudis are determined will be sponsored only by Sunni powers and not, as was historically the case, by Iran.)

Tehran has a long history of funding subversion around the Gulf, relying on disgruntled Shiite populations when it can. Most of our traditional friends in the region worry about this, about the slaughter of Sunnis in Syria, and about the Shiite ascendance in Iraq more than they worry about the rise of the Islamic State.

There are already checks on Iranian misbehavior in the Gulf. For example, when 1,500 Saudi and UAE troops rolled over the causeway into Bahrain during that country’s Arab Spring uprising, which aimed at giving the Shiite majority more political power in that Sunni monarchy, it sent a strong signal to Iran that fomenting Shiite unrest would not be tolerated. Further protection against Iranian troublemaking in the Gulf could be developed through greater intelligence cooperation between the regional governments and the United States. But the Sunni monarchies are unlikely to want the help if it comes at the cost of a more intimate relationship with U.S. intelligence. These governments don’t want the United States peering under the hood and they won’t want demands for greater respect for human rights – including those of Shiite citizens — that might accompany deeper relationships, especially from Congress.

So what does this all add up to? Perhaps the fairest way to put it is that the evidence suggests Iran will use some of the funds it receives from sanctions relief to shore up its position in Syria and to fuel competition against Sunnis across the Middle East. But terrorist attacks directly against the United States are a low probability. Israel, a close ally, always stands to lose when Iran is strengthened, but it still is unlikely to see a major change in the terrorist threat — and certainly no strategic change that could compare with the advent of an Iranian nuclear capability.

The United States needs to remain watchful and engaged in the Middle East, but the nuclear deal ought to stand or fall on its own merits — on such questions as whether the verification strictures, enrichment requirements, and disposal of possible weapons materials are sufficient. Those who argue that the terrorist consequences are too great to countenance a deal are mistaking their loathing for the Iranians — who have provided plenty of reasons to be loathed — for real analysis.

This piece was originally published by Foreign Policy.