President Donald J. Trump’s announcement that the United States is “withdrawing” from the Iran nuclear deal, the Joint Comprehensive Plan of Action, was greeted with considerable enthusiasm by many Gulf Arab leaders. The announcement offers the prospect of a new era of U.S. leadership aimed squarely at rolling back Iranian hegemony in the region, and possibly even a campaign of regime change in Tehran. Much of what Trump said encourages such hopes. But serious questions linger over the actual trajectory of U.S. Middle East policy and Washington’s willingness to pay the price required to achieve such goals. And if the evolving situation has all the elements of a hypothetical wish-fulfillment scenario for Saudi Arabia, the United Arab Emirates, and perhaps some other Gulf Cooperation Council countries (though GCC opinion is divided) a closer look reveals the potential for a more troubling turn of events as the international nuclear agreement with Iran begins to crumble.

The Gulf Arab countries and Israel – often referred to collectively as Washington’s key Middle East allies – were arguably the international actors most uncomfortable with the nuclear negotiations with Iran and subsequent agreement. But their priorities differed somewhat, especially as the JCPOA was implemented in 2015. Israel was squarely focused on Iran’s pursuit of a nuclear weapon, while Gulf Arab countries prioritized Iran’s growing regional hegemony and support for nonstate extremist groups. After receiving U.S. assurances, the Gulf countries did endorse the negotiations, and ultimately the agreement, albeit with evident misgivings.

In an important strategic shift since 2015, however, Israel’s views have moved closer to the Gulf Arab perspective of emphasizing the need to contain and roll back Iran’s expanding influence. With the fall of rebel-held parts of Aleppo to forces supportive of the Syrian regime in the early weeks of 2016, the main phase of the Syrian war effectively ended, leaving Iran and its allies in control of much of the country and enormously strengthened. Hizballah, in particular, has emerged from the conflict much stronger and with a far more robust, wide-ranging presence, cementing its role as a regional vanguard force for pro-Iranian armed, nonstate groups. Moreover, various armed groups hostile to Israel began to consolidate positions near its borders and the Israeli-occupied Golan Heights.

Anxieties were only heightened in Israel and the Gulf countries when, as the Islamic State in Iraq and Levant’s self-declared caliphate in western Iraq and eastern Syria crumbled in 2017, pro-Iranian forces seized strategic positions on both sides of the Iraqi-Syrian border. These developments have made plausible the creation and consolidation of an Iranian-controlled military corridor or “land bridge” running through Iraq and Syria linking Iran with Lebanon (and Hizballah) and the Mediterranean coast. Meanwhile, evidence of Iranian and Hizballah activity in Yemen, Bahrain, and beyond mounted, while Israel began to launch military actions against Iranian and Hizballah targets in Syria. Israel claimed Iran launched an armed drone into its airspace from Syria – which the Israeli military shot down – and both Riyadh and Washington have blamed Iran for a series of Houthi missile attacks from Yemen targeting Saudi cities. Shortly after Trump’s announcement, Israel went on “high alert” in the occupied Golan Heights, including preparing bomb shelters.

Therefore, the perception of an Iranian threat shared by Israel and Gulf Arab countries has intensified and grown more congruent since 2015. In his JCPOA statement, Trump specifically cited Israel’s revelation of archives documenting elements of the Iranian nuclear weapons program before the signing of the JCPOA. Outside of Israel and the United States, the Trump announcement probably resonated most strongly in some Gulf Arab countries. Indeed, when the Israeli military chief of staff, Lt. Gen. Gadi Eisenkot, was interviewed by the leading Saudi news site Elaph in 2017, his description of the Iranian threat and what should be done to counter it was virtually indistinguishable from many Gulf Arab perspectives.

However, while Israel’s political leaders, particularly Prime Minister Benjamin Netanyahu, wanted Trump to simply abandon the agreement, many Gulf Arab voices were counseling him to use the JCPOA as leverage on Iran’s destabilizing regional policies. There have been reports that European negotiators were able to agree with Trump administration officials on addressing Iran’s missile testing and malign regional conduct, although the parameters of these understandings have not been revealed. But negotiations between Washington and the E3 European signatories to the JCPOA (France, Britain, and Germany) reportedly collapsed over the “sunset clauses” in the JCPOA after which certain restrictions on Iran’s nuclear activities would have technically expired. So, it is possible that while the Israeli government is getting exactly what it wants, Gulf Arab countries might have been even better off with the supplementary arrangements that were never fully agreed upon. Nonetheless, many Gulf Arabs will be delighted by Trump’s strong condemnation of Iran’s regional agenda and especially its “sinister activities in Syria, Yemen, and other places all around the world.”

Gulf Arab concerns about the JCPOA also reflected their worries about the legitimacy they feared it bestowed on the Iranian regime and the prospect of a broader rapprochement between Washington and Tehran. Hopes undoubtedly now run high among these leaders that the United States now intends to aggressively confront, contain, and even roll back Iran, especially given the passage in the presidential memorandum Trump signed stating that U.S. policy is that “Iran’s network and campaign of regional aggression be neutralized,” and further, “to disrupt, degrade, or deny the Islamic Revolutionary Guards Corps and its surrogates access to the resources that sustain their destabilizing activities.” For Saudi Arabia, the UAE, and Bahrain, at least, the minimal goal is ensuring no further expansion of Iran’s growing regional influence. A medium goal is an end to Iran’s destabilizing policies, such as support for a wide range of nonstate actors in the Arab world. And a maximal goal would be regime change.

Iran’s economy is in dire straits despite a recent uptick in the price of oil, and the country has been rocked with protests and deep divisions. Enthusiasts in Tel Aviv, Riyadh, and Washington will be hoping that without the sanctions relief provided by the JCPOA, and with Trump’s instituting what he pledges will be “the highest level of economic sanction,” a campaign of economic attrition will begin to reverse the expansion of Iran’s regional influence since the U.S. invasion of Iraq in 2003. Over time, proponents of this approach hope this pressure, combined with limited and targeted regional military actions against pro-Iranian nonstate actors, possibly even through proxy forces, can begin to roll back some of the gains made by Iran in parts of the Arab world such as Syria, Yemen, Iraq, and even Lebanon. Some may even expect that such a policy, if it is sustained, will dovetail with Iranian popular discontent and political divisions to create an atmosphere of comprehensive foreign-policy change, if not regime change in Tehran.

However, merely reinstituting, or even expanding, the sanctions lifted by the JCPOA is, on its own, unlikely to produce any of those results. Signing presidential memos and executive orders is easy. Confronting Iran on the ground in the region will be much more difficult. Other recent developments prompt serious doubts about the Trump administration’s willingness to take the kind of actions required to significantly restructure the strategic equation in the region. If the Trump administration had been looking for an opportunity to deter what the president called Iran’s “sinister activities” in Syria, the recent missile strikes following a chemical weapons attack by the regime of President Bashar al-Assad provided an obvious opportunity. Yet Trump’s action carefully avoided not only any Russian-related targets, but also anything related to Iran or Hizballah. It even avoided any targets crucial to the Assad regime and seemed to suggest that Russian and Iranian deterrence were working well.

Moreover, Trump vowed to withdraw all U.S. troops in eastern Syria, which would have left pro-Iranian forces poised to seize the last remaining strategic areas needed for a land bridge. He was apparently dissuaded from that course of action, but it suggests a degree of cognitive dissonance between the strong words Trump used in rejecting the JCPOA and a much greater sense of cautionwhen it comes to the practical application of U.S. armed force. Either Washington is going to take the lead in such theaters, or it is going to insist that “other people” can take care of things, and right now both of these mutually exclusive impulses seem to be fully operative.

Furthermore, if Washington does take the lead in a broad and sustained campaign to pressure Iran on multiple fronts, both sides in the internal GCC dispute can expect significant pressure. Qatar will have to be extremely careful about limiting its relationship with Tehran, including economic ties, and what attitudes toward a potential conflict with Iran are promoted by Al Jazeera Arabic and various Doha-funded media outlets. Saudi Arabia, the UAE, and Bahrain, on the other hand, along with Egypt, may find that if the Trump administration is leading such a focused campaign to pressure Iran it will become much more impatient for a resolution of the boycott of Qatar, especially given the crucial U.S. military bases and assets there. Thus far, Washington has not made any aspect of bilateral relations with any of these parties contingent on an end to the boycott, but in the context of a new focus on Iran that could certainly change.

Of all the principals in the budding alliance to confront Iran, the Gulf Arab states may be the most exposed. Tehran predictably responded to Trump by emphasizing its determination to persist with the JCPOA and the other five signatories no matter what, posing as the victim and the responsible international actor. There is certainly potential for a clash between Israel and Hizballah, and possibly even Iran, in Syria, and that could spread to Lebanon. But, thus far, both sides appear determined to avoid such a confrontation. The most obvious hotspot is Yemen, where Saudi and Emirati forces are combating a range of nonstate foes including the Houthis and al-Qaeda. Houthi missile strikesagainst Saudi Arabia are already a regular occurrence, and it’s easy to imagine an intensification of such attacks. Proxy conflict could spread in Iraq, Syria, and possibly Bahrain. Iran has considerable resources, and Gulf Arab targets will be the most vulnerable, and therefore tempting, should the struggle greatly intensify.

Finally, hopes that the U.S. withdrawal from the JCPOA will initiate a major new campaign to pressure Iran assume there will be a coherent and practicable Plan B led by the United States. If Washington proves to lack the vision, commitment, or ability for such a campaign, the consequences could be disastrous. Iranian hard-liners could find themselves greatly strengthened, freed from both the comprehensive international sanctions regime that led to the JCPOA and also from their own nuclear commitments under the accord, and with very few direct constraints on their regional malfeasance. Any Gulf countries that are bracing for such a confrontation cannot prevail against Tehran on their own, and they cannot rely on Israel. They are banking on Washington to use as much U.S. might as necessary to ensure that, at a minimum, the strategic landscape is rearranged sufficiently to bring Iran to reasonable terms with them. After Trump’s JCPOA withdrawal, enthusiasm may be running high in some quarters over the likelihood that Iran will experience a great deal of pain in the coming months. But whether Tehran will suffer a meaningful strategic reversal is much less clear.