Chapter One: Tehran’s strategic intent

On 19 March 2003, American cruise missiles hit Baghdad, beginning a series of high-intensity, precision salvos. Within three weeks, the US-led international coalition had occupied the Iraqi capital and effectively ended a regime that Iran had failed to defeat during the eight-year Iran–Iraq War, a conflict that had consumed a generation of Iranians and crippled Iran’s economy.

Within months, Iran had executed the initial stages of an aggressive hybrid-warfare strategy1 aimed at frustrating US objectives in Iraq, while simultaneously attempting to reshape Iraq’s political dynamic to favour Iran. The campaign drew upon a military doctrine that acknowledged Iran’s conventional military weakness and avoided direct confrontation with powerful adversaries. The doctrine eschewed operations that might invite heavy casualties and instead focused on the use of unconventional forces and proxies.

Relying on unconstrained logistics lines, Tehran exported a relatively seasoned group of Iran-based Iraqi surrogates and developed its first foreign militia since the creation of Lebanese Hizbullah. Iran enabled these militias by providing military technology that was tailored for its lethality to Western military forces. The rapid collapse of political stability in Iraq, combined with an absence of a Western strategy either to prevent or levy a price for Iran’s intervention in Iraq, allowed Tehran to manipulate the political evolution of a collapsed Arab state for the first time since Lebanon in the 1980s. By 2011, Iran’s forces and political allies were entrenched in Iraq, and Tehran’s influence there acknowledged by the international community.

The collapse of Syria in 2011 threatened Iran with the loss of its only state ally and the logistical architecture it relied upon to sustain Lebanese Hizbullah. Furthermore, the intensity of the Syrian civil war challenged a military doctrine best suited for low-intensity conflict. However, an unconstrained logistics channel in the form of an air bridge, the availability of nearby surrogates, and the absence of any Western effort to block Iran’s involvement during a time of diplomatic engagement on nuclear issues allowed Tehran time to shape a strategy that achieved objectives without challenging its fundamental doctrinal principles.

However, Iran’s regional adventurism required a domestic narrative to blunt opposition. Tehran’s state-controlled media and religious institutions initially masked or minimised its involvement in Syria, framing its actions as the protection of Syria’s Shia community and important shrines from Sunni militants. Potential domestic criticism was stifled by aggressive state-security elements or muted in the wake of Sunni militant terrorism in Ahvaz and Chabahar in 2018, which validated the need for extraterritorial counter-terrorist operations. Although the extent of personnel losses and resource costs would eventually be revealed, domestic opposition never reached the point where Iran’s leaders needed to consider compromise on critical objectives, let alone withdrawal from the conflict.

The unexpected fall of the Yemeni city of Sanaa to the Houthi rebels in September 2014 provided Iran with an opportunity to inflict damage on Saudi Arabia and the United Arab Emirates for the first time since the Islamic Revolution in 1979. By then accustomed to an absence of Western reaction to its interventions, Tehran might also have considered the Yemen conflict as a chance to extend Iran’s influence into the southern Red Sea.2 However, intervention in this conflict would not be easy. Tehran’s focus at the time could not be shifted from Syria, and its logistics channel to Yemen would be constrained. Iran’s relations with the Houthi leadership extended to the first days of the 1979 revolution, but the political and operational connections were shallow compared to those with the Syrian regime. The Houthis brought years of experience as insurgents, but their battlefield sophistication was more akin to that of the Taliban than Lebanese Hizbullah. Once again, an unconstrained, if less efficient, logistics channel and the absence of international opposition eventually enabled Iran to introduce advisers, funds, advanced ballistic-missile technology, armed uninhabited aerial vehicles (UAVs) and explosive remote-controlled boats, which significantly altered the course of the conflict.