Unlike Iran’s nuclear program, the country’s arsenal of ballistic missiles has received only scant scholarly attention. At best, some highly technical analyses have been offered. At worst, the missiles have been considered only as part of the nuclear project, designed to carry nuclear warheads. However, the missile program is a complex and sophisticated response to Iran’s unique security challenges, and should be analyzed on its own.

The signing of the Joint Comprehensive Plan of Action (JCPOA) in July 2015 has made this task more urgent. With the nuclear program rolled back, Iran’s missiles have become a new target of international attention. The ballistic program is run by the Revolutionary Guards, which has been subject to numerous sanctions because of its alleged terror activities.

The focus is especially intense in Washington, where the Obama administration’s drive to conclude the nuclear accord was divisive. For instance, some critics urged imposing a new round of sanctions on Iran to curb its missile program. Others suggested using American anti–ballistic missile defense capabilities in the region to target Iranian ballistic trials. According to this rational, denying the Revolutionary Guards the ability to test missiles would disrupt its research and development opportunities.

Both courses of action have potentially far-reaching consequences. Slapping more sanctions may prompt Tehran to abrogate the JCPOA. Intercepting the missiles of a sovereign country violates international law and may lead to a huge conflagration in the Middle East and beyond. Given the high-level stakes of these policies, an analysis of Iran’s rationale for developing its ballistic arsenal is in order.

Intentional-relations theory indicates that the decisions that drive the proliferation of nuclear weapons are quite similar to those that prompt the quest for a ballistic-missile program. Both nuclear weapons and ballistic missiles are instruments of power that may be used as deterrent or compellent threats. They both serve to enhance the security of a state through raw power. As John Mearsheimer, a leading realist theorist, put it, states always strive to maximize their power over their rivals, with hegemony as their ultimate objective.

A large body of research indicates that states make rational choices when deciding to proliferate or acquire a ballistic arsenal. In the case of Iran, however, discussions of the regime’s motives are underpinned by rational choice theory of varying degrees of rigor. At best, some analysts seek to apply the restrictive mathematical basis of formal rational-choice models; at worst, it is a projection of the authors’ views of what rational behavior should be.

Absent conclusive evidence to prove or disprove either side, the discourse has turned into a profession of faith. As one observer put it, when it comes to Iran, rationality or lack of it is in the “eye of the beholder.”

Developing indigenous missile and anti-missile systems has been a key components of Iran's deterrence strategy. The regional tension between Iran and its powerful neighbors goes a long way toward explaining why Iran feels the need for greater defense capabilities. Iran was forced to consider nuclear and ballistic options because of its long and bloody war with Iraq, which had a profound role in shaping Iran’s strategic thinking.

The history of the bloody conflict between the two countries is well known. The second-longest war of the twentieth century, it has been frequently compared to World War I. Like the 1914 war, it relied on trench warfare, human wave attacks, indiscriminate assault on civilian populations and, most importantly, Iraq’s use of chemical weapons against Iranian soldiers and civilians.

Although Iran’s dedication to exporting its revolution, a goal that the regime was not willing to forgo in the face of extreme hardship, exacerbated the conflict, the war left deep and enduring scars on the Iranian collective psyche. Even a casual perusal of cultural narratives indicates a deep sense of insecurity and vulnerability.

Thus, the leadership concluded that Iran would need a powerful deterrent of some kind.

But the embargo on weapon sales pushed by the United States after activists seized the American embassy in Tehran in November 1979 proved to be a huge obstacle for obtaining a strong deterrent. Strained relations with the United States even made it difficult for Iran to access technology needed to maintain its air force. Obtaining standard weapons and munitions on the black market involved extremely complex arrangements. Things got much worse when, at Iraq’s request, the United States launched Operation Staunch, a global ban on the sale of weapons to Iran in 1983.

The weapons embargo led the regime to believe that, ultimately, Iran must rely on its own resources for self-defense. From Tehran’s point of view, such a decision was a highly rational step—one that met the criteria for many of Kenneth Waltz’s proliferation factors.

Struggling to rebuild a traditional army and air force in a dangerous neighborhood, they opted for a ballistic shortcut. Technologically, missile production, as envisaged by Hassan Tehrani-Moghaddam, the father of Iran’s ballistic-missile program, was close to ideal for a country that had enshrined “self-sufficiency” in its security doctrine. A ballistic arsenal was also a rational response to Washington’s long-standing policy of arming and protecting its allies in the region.

Even for a region known for its epic conflicts, the prodigious spending on the arms race stands out. Most striking is the growing level of sophistication in arms and related weapons technology among the Arab Gulf states. For instance, Gulf Cooperation Council member countries spend approximately $98.5 billion on their militaries annually, compared to Iran’s $10.6 billion. Data released by the U.S. Congressional Research Service indicates that the GCC acquired $38.5 billion worth of new arms between 2004 and 2011, thirty-five times more than Iran’s acquisition of $1.1 billion for the same period. Similarly, data released by the Stockholm International Peace Research Institute indicates that the Gulf states have a massive lead over Iran in terms of spending on military munitions.

In addition to cutting-edge military wares, the Gulf countries enjoy access to superior American training, Intelligence, Surveillance and Reconnaissance systems, and Command, Control, Communications, Computer, and Battle Management capabilities (C4I/BM). Because of American C4I/BM, the Gulf countries face virtually no technological risks when choosing combat systems. Iran, on the other hand, faces risks in performance, delivery delays and unanticipated costs in its self-produced systems.

Israel, another archrival of  Iran and the only country in the Middle East believed to possess nuclear weapons, can fit its ballistic missiles with nuclear payloads, which is great concern for the Iranians.

In addition to receiving total direct aid of over $140 billion from the United States since the October War in 1973, Israel enjoyed a joint American-Israeli project estimated at some $3 billion, resulted in an integrated multilayered, anti-ballistic system: the short-range Iron Dome, the mid-range Jericho and the long-range Arrow. Linked to the FBX-T Raytheon radar systems, known popularly as the X-band, it is part of the Joint Tactical Ground Station Theater Warning System based in Europe but operated by American personnel in Netivot in the Negev.

Moreover, as part of a “compensation package” for the JCPOA, Israel demanded a squadron of advanced F-15 Strike Eagles and V-22 Osprey tilt-rotors planes, reportedly worth more than $3.1 billion. It was reported that the Israelis asked for Boeing’s F-15SE Silent Eagle derivative, equipped with Radar Cross Section reduction features and internal weapons bays housed inside the jet’s conformal fuel tanks.

From Tehran’s perspective, Washington’s policy of arming its allies has threatened its security interests, not to mention its deterrent power. Seen within this context, Iran’s effort to develop a nuclear arsenal is a rational response to a security dilemma. Suffering from extreme sanctions that eroded the economy and put the very legitimacy of the regime in peril, Iran’s leaders decided to sign the JCPOA. With the nuclear option gone, at least for the duration of the accord, the importance of ballistic missiles for defense and power projection has increased.

But since ballistic missiles capable of carrying a nuclear warhead are an integral part of a nuclear arsenal, some critics argue that Iran’s efforts to develop its ballistic-missile capabilities may reflect its desire to continue with its nuclear-weapons program. This is a justifiable suspicion because of Iran’s record of conducting covert nuclear activities (“possible military dimensions”) at nuclear sites such as Parchin and Kolahdouz military complexes.

If PMD tests are the nuclear equivalent of “smoking gun” evidence, ballistic missiles do not constitute equivalent proof, since they can be used in both a defensive and offensive capacity. Ballistic missiles can be equipped with conventional warheads, although it is assumed that in long-range missiles, a conventional warhead is not cost effective. Medium-range missiles, however, pose a dual-use problem for intelligence analysts who investigate them, and for politicians who must devise ways to respond to them.

But perhaps the most important implication of the JCPOA and the IAEA verification process is that Iran’s ballistic missiles will only be conventionally armed for a decade or more. If Iran does not have the fissile material to make a nuclear weapon and attach it to its missiles, they pose no threat to Iran’s adversaries. Due to their poor accuracy, the military utility of Iran’s missiles is limited, and they are therefore not likely to be decisive if armed with conventional warheads. Michael Elleman, an expert on missiles at the International Institute for Strategic Studies, noted that despite recent gains, Iranian missiles remain too inaccurate to reliably destroy specific military targets. In the end, the function of the missiles may be more psychological than kinetic; if the regime believes that the missiles can deter and possibly intimidate its regional adversaries, securing the continuation of the program may help the moderate president Hassan Rouhani and his followers to maintain support for the JCPOA.