Why Iran fights its wars abroad: The logic and cost of forward defence

Wars are often remembered by the armies that fought them. But in the Middle East, the most consequential conflicts of the past four decades have frequently been fought by those who were never officially at war. Militias, resistance movements, armed political organisations and local factions have become the preferred instruments of power. At the centre of this architecture stands Iran's "forward defence doctrine"—a strategy that seeks security not by fortifying borders, but by extending influence beyond them.

Much of the international conversation asks what Iran's proxies do. A more revealing question is why Iran depends on them in the first place. The answer lies in a combination of military calculations, historical experience, geography and ideology. Over time, however, this strategy evolved into one of the Middle East's most influential—and destabilising—systems of proxy warfare. A doctrine born out of insecurity has since become one of the principal drivers of instability across the Middle East.

The roots of this strategy lie in the Iran-Iraq War (1980-1988), which left hundreds of thousands dead and exposed Iran's diplomatic isolation: Saddam Hussein's Iraq drew financial and military support from Arab states and Western powers while revolutionary Iran largely stood alone. Tehran emerged convinced that waiting for enemies to reach its borders was an invitation to catastrophe, and that if conflict was inevitable, better that it be fought in southern Lebanon, northern Iraq or the Syrian desert than in Tehran or Isfahan.

Conventional competition was never a realistic option in any case. Decades of sanctions have constrained Iran's access to advanced aircraft, naval platforms and sophisticated weapon systems, and its air force still relies heavily on hardware acquired before the 1979 revolution. Rather than attempt to match the United States, Israel or Saudi Arabia directly, Iran concluded that deterrence could be achieved more effectively and far more cheaply through asymmetric means.

Why proxies became Iran's preferred weapon

Supporting regional armed groups delivers strategic depth at a fraction of the cost of maintaining expeditionary forces or modernising entire military branches. Training fighters, providing missiles, intelligence and financial assistance is significantly less expensive than building aircraft carriers or fifth-generation fighter fleets. More importantly, such partnerships create influence that conventional armies often cannot.

A useful analogy is insurance. Most people never hope to use it, but they pay premiums because uncertainty is expensive. Iran's network of allied groups functions similarly. Hezbollah in Lebanon, various Iraqi militias, Syrian allied forces and Yemen's Houthis collectively provide Tehran with multiple layers of deterrence. Any attack on Iran risks triggering responses across several theatres simultaneously.

This "distributed deterrence" complicates military planning for adversaries. An Israeli strike on Iranian nuclear facilities, for instance, cannot be assessed solely in terms of direct retaliation from Iran. Decision-makers must also consider rocket attacks from Lebanon, militia operations in Iraq, disruptions to shipping routes or escalating regional tensions. By creating uncertainty, Iran seeks to raise the political and military costs of confronting it.

The doctrine also reflects geography. Iran occupies a strategically vulnerable neighbourhood. To its west lie Iraq and Syria, historically invasion routes. To the south sit the energy-rich Gulf monarchies hosting American military bases. To the east lie Afghanistan and Pakistan, both sources of prolonged instability. Iran's leadership has long viewed its regional environment as exceptionally hostile.

Iran therefore seeks buffers rather than borders. Aligned armed groups extend Iran's influence beyond its borders and provide additional avenues for deterrence. Military strategists have long argued that strategic depth matters. For Iran, strategic depth is measured less in kilometres than in networks of influence.

Ideology further strengthens these relationships. Unlike purely transactional alliances, many of Iran's partnerships are built around a shared narrative of resistance against foreign intervention and perceived Western or Israeli dominance. This ideological dimension generates loyalty that financial incentives alone cannot purchase. It explains why groups often continue cooperating with Tehran despite facing enormous military pressure.

History offers several examples of great powers relying on local allies rather than conventional occupation. During the Cold War, both the United States and the Soviet Union armed friendly governments and insurgent groups across Asia, Africa and Latin America. Empires have long discovered that local partners understand terrain, language and politics better than foreign armies ever can.

Iran has adapted this long-standing model into one of the most sophisticated proxy networks of the twenty-first century.

Yet there is a profound contradiction embedded within the doctrine. Every measure intended to increase Iran's security often decreases the region's security.

The problem lies in perception

What Iran interprets as defensive preparation is viewed by neighbours as offensive expansion. When Tehran supplies missiles to allied groups, it sees deterrence. Israel perceives encirclement. Gulf monarchies perceive subversion. The United States sees threats to regional stability. Each side reacts to the other's defensive measures with its own military build-up, producing a classic security dilemma where everyone feels less secure despite spending more on security.

Lebanon illustrates this paradox vividly. Hezbollah undoubtedly deterred future Israeli invasions after 2006 by developing formidable military capabilities. At the same time, its military strength transformed Lebanon into a recurring battleground during periods of regional confrontation. Ordinary Lebanese citizens increasingly find themselves paying the price for strategic calculations made far beyond their control.

Syria offers another cautionary tale. Iranian support helped preserve Bashar al-Assad's government during the civil war, preventing the collapse of one of Tehran's closest regional allies. But sustaining that alliance also internationalised the conflict, drawing in Russia, Turkey, Israel, Gulf states and Western powers. What began as a domestic uprising evolved into one of the world's most destructive proxy wars.

The economic consequences are equally significant. Iran has invested billions of dollars supporting regional allies while facing inflation, unemployment and periodic domestic unrest. Critics inside Iran increasingly question whether resources devoted to external conflicts should instead address deteriorating living standards at home. The slogan heard during several Iranian protests—"Neither Gaza nor Lebanon, my life for Iran"—captures this growing tension between ideological ambitions and domestic priorities.

Ironically, forward defence may also produce strategic overextension. Maintaining influence across multiple conflict zones demands continuous political attention, financial resources and military commitment. History repeatedly demonstrates that powers stretched across numerous theatres often struggle to sustain their ambitions indefinitely. The British Empire, the Soviet Union and even the United States have all confronted the burdens of maintaining extensive overseas commitments.

The recent regional escalations involving Israel, Iran and various non-state actors further demonstrate another limitation of the doctrine. Proxies provide plausible deniability only up to a point. As regional intelligence capabilities improve and military technologies become increasingly precise, distinguishing between the actions of allied groups and those of their state sponsors becomes more difficult. Escalation that was once indirect increasingly risks becoming direct.

This raises an uncomfortable question: has the doctrine outlived the strategic conditions that made it successful?

Forward defence undoubtedly achieved important objectives for Iran. It expanded influence despite sanctions, deterred direct attacks for decades, prevented strategic isolation and enabled Tehran to project power without matching conventional military rivals. Judged narrowly through the lens of regime survival, it has been remarkably effective.

But judged through the broader lens of regional peace, the record is far less convincing.

The Middle East today resembles a neighbourhood where every household installs higher walls because everyone fears their neighbours. Each new wall reinforces the belief that danger is growing, prompting others to build even higher ones. Eventually, the architecture of fear becomes self-sustaining.

Iran's forward defence doctrine embodies this dilemma. It emerged from deeply rooted security anxieties shaped by the Iran-Iraq War and decades of regional confrontation. Yet by externalising those anxieties through armed networks across the region, it has contributed to a cycle in which deterrence and instability reinforce one another.

The real tragedy is that every actor involved believes it is acting defensively

Until the region develops security arrangements that reduce this mutual fear rather than amplify it, Iran will continue investing in proxies, its rivals will continue investing in countermeasures, and the Middle East will remain trapped in an endless contest where no side feels secure, even as all sides become increasingly armed. The doctrine may have protected Iran from isolation, but it has also helped institutionalise a permanent state of insecurity across the region—a strategic success with profoundly destabilising consequences.