On Tuesday July 15, the P5+1 and Iran finalized an agreement that places significant limits on Iran’s nuclear program for the next twenty-five years. The most important aspects of the Joint Comprehensive Plan of Action (JCPOA) are the intrusive inspection mechanisms, designed to monitor Iran’s centrifuge production facilities and uranium mines for twenty years, before giving way to the continued enforcement of the International Atomic Energy Agency’s Additional Protocol—a voluntary inspection regime designed to strengthen the Agency’s ability to detect the diversion of nuclear material for non-peaceful uses.

These inspections are designed to prevent so-called “sneakout,” wherein Iran could clandestinely syphon off mined uranium, convert it to gas, and then spin it in an undeclared centrifuge facility. The detection of clandestine gas centrifuge sites is exceedingly difficult, owing to the small size of the building needed to house weapons-specific centrifuge cascades, and the minimal amount of power needed operate such a facility. The JCPOA leaves little chance, ensuring that the United States and the IAEA will have a full accounting of where Iran’s gas centrifuges are manufactured, while also monitoring these sites in real time for twenty years. On its nonproliferation merits, the deal succeeds in raising the threshold for detection, should Iran decide to divert nuclear material for non-peaceful uses.

However, one should not perceive the agreement as a stepping-stone toward a mechanism to ensure closer US and Iranian cooperation in the region—particularly in Iraq. The two countries have divergent political and military aims, despite the shared threat of the Islamic State (ISIS or ISIL). While the United States has indirectly supported Iranian-backed Shia militias in Iraq—notably through providing air power in certain instances—this cooperation masks broader political divergences about the future of Iraqi state.

As a condition of extending airstrikes beyond Iraqi Kurdistan, the United States helped orchestrate the removal of former President Nuri al Maliki, in favor of the more inclusive-minded Haider al-Abadi. Iran, however, has consistently undermined Abadi, often times working through Maliki to undermine Abadi’s US-backed efforts to address Sunni grievances. Iran is also deeply involved with a number of Shia militias, including the Badr Brigade under the command Hadi al-Ameri.

Ameri and Iranian-backed Shia militias have grown bolder in challenging Abadi’s authority, whose popularity has waned after the Iraqi Army’s disastrous defeat in Ramadi in May. Abadi has sought to bring Shia militias under the control of Iraqi state, but Ameri-controlled Shia militias have ignored government orders, launching raids into Fallujah as the central government touts its plan to retake Ramadi.

Abadi faces two challenges: First, Iran’s funding of Shia militias has undercut his leverage with men like Ameri, thereby limiting his control over the Shia militias. This policy detracts from his popularity at the expense of Ameri, who is portrayed as a war hero in Shia media. Second, regional Sunni states have sought to counterbalance Iran’s influence, working through Sunni proxies to prevent the passage of another key US-backed proposal: a national guard law. This Abadi and US-backed proposal would create a legal structure to oversee the Shia militias, while also putting in place a mechanism to create Sunni militias operating under central government control. The Turkey-allied Sunni political party Mutahidun has balked at this proposal, arguing that the militias should answer to the local governor and remain independent from Baghdad—creating a counterweight to Iranian backed Shia militias and a pathway for disaffected Sunnis to join a locally raised militia.

This intra-Sunni discord has prevented the passage of the bill, detracting from the overarching effort to undercut ISIS’s appeal in Sunni-majority areas. For the regional states opposed to Iran’s involvement in Iraq, the creation of a Sunni majority militia beholden to a governor loyal to an outside power has some appeal. Yet, beyond this narrow zero-sum approach, the Iraqi security services’ divergent loyalties undermines the country’s long-term viability as a cohesive state.

The United States is committed to working through Baghdad, owing to its adherence to the “one Iraq policy” it put in place after the 2003 invasion. Iran shares this goal of keeping Iraq united, but they differ in tactics. Washington would prefer that Baghdad gain in strength and monopolize the use of force, with the near-term objective of defeating ISIS and the longer-term aim of creating a stronger Iraqi society to keep the country united. Iran, on the other hand, wants Baghdad to remain weak to retain its leverage with key Iraqi politicians, to both ensure that Iraq satisfies its political interests and prevent political outliers from threatening its long-term security interests. This critical divergence is currently playing out in the war against ISIS.

To deal with the immediate threat of ISIS, Iran has carved out a de facto buffer zone from the relatively stable—and Shia majority—Basra province, through Baghdad and Diyala, and into eastern parts of Iraqi Kurdistan. It has also supported the Kurdish Peshmerga, choosing to primarily operate through the Patriotic Union of Kurdistan Party (PUK)—a political party with strong economic and political links to Tehran. Iran views its support for the PUK as a key component of its efforts to ensure that Iraqi Kurdistan remains a part of Iraq, despite its autonomy.

Compare this to the United States, which has resisted numerous calls to arm the Kurdistan Regional Government (KRG) directly, instead routing arms destined for the Kurds through Baghdad. This proposal is, in part, based on the fact that the PUK’s political rival, the Kurdistan Democratic Party (KDP), takes control of weapons shipments and then provides them to PUK controlled Peshmerga. Thus, from the US perspective, the direct provision of arms to the KDP could further undermine Baghdad’s authority in the KRG, while also creating intra-Kurdish political tensions—both of which detract from the one Iraq policy.

Looking beyond the narrow convergences over macro issues like defeating ISIS and maintaining a united Iraq, the United States and Iran appear diametrically opposed in the tactics meant to bring this about. These dynamics undermine the notion that the nuclear deal will help bridge the gap between the United States and Iran. Instead, the deal represents a narrow convergence of shared interests: intrusive inspections and the rolling back of Iran’s nuclear program in return for sanctions relief.

In the coming days and weeks, the United States would be wise to temper expectations and narrowly cast the nuclear deal as a nonproliferation specific agreement, designed solely to address Iran’s nuclear program. This rhetoric should be paired with a more concerted effort to align Washington’s approach in Iraq with those of its closest allies. This will not be easy, but it is necessary to prevent a united front to check Iran’s ambitions in Iraq and ultimately serves to advance Washington’s preference for a strong and united Iraq in the future. Such action could help ease the suspicion that Washington is eager to pair with Tehran to defeat ISIS and jointly run Iraq in the future. Instead, the United States should commit to advancing its own interests in Iraq. This goal would require taking the necessary political steps to decrease Iranian influence.

Aaron Stein is a Nonresident Fellow with the Rafik Hariri Center for the Middle East, a Doctoral Fellow at the Geneva Center for Security Policy, and an Associate Fellow at the Royal United Services Institute in London.

Image: US Secretary of State John Kerry speaks with Hossein Fereydoun, the brother of Iranian President Hassan Rouhani, and Iranian Foreign Minister Javad Zarif after agreeing on a nuclear deal, July 14, 2015. (Photo: US State Department)