Why Iran is banking on its swarm warfare doctrine as conflict with US looms

In a statement issued on January 28, US President Donald Trump urged Iran to enter negotiations and reach an agreement on the nuclear issue, warning that failure to do so could lead to severe consequences.

Trump said, “The next attack will be far worse! Don’t make that happen again,” once again emphasising that a US armada was being deployed towards Iran.

US Central Command also announced that a strike group led by the USS Abraham Lincoln had arrived in Middle Eastern waters.

Against this backdrop, Iran has been experiencing a wave of protests in recent weeks, triggered by the sharp depreciation of its currency, the rial, and worsening economic conditions. 

Beginning on December 28 in Tehran’s Grand Bazaar, the protests quickly spread throughout the country. 

According to a US-based human rights group, the confirmed death toll had reached 6,373 by the thirty-second day of the protests, with 42,486 individuals reportedly detained. Iranian official sources, however, claim that the number of fatalities stands at 3,117.

What sets the latest protests in Iran apart from earlier episodes of unrest is President Trump’s clear support for the protesters and his openly threatening rhetoric towards Iranian leaders.

Indeed, in a post on his Truth Social account on January 2, Trump stated that “if Iran shoots and violently kills peaceful protesters, which is their custom, the United States of America will come to their rescue”.

By characterising such practices as customary, he signalled that the United States was prepared to respond. Subsequent statements by Trump along similar lines further reinforced, more than at any time before, discussions in Iran regarding scenarios of US military intervention and government change.

In response, Iranian officials have consistently maintained that they remain open to negotiations based on mutual respect and equality, while insisting they will not retreat in the face of threats. 

Most recently, in a post on X dated January 29, Iranian Foreign Minister Abbas Araghchi responded to Trump’s threats by stating that “Our brave Armed Forces are prepared—with their fingers on the trigger—to immediately and powerfully respond to ANY aggression against our beloved land, air, and sea,” while also noting that Iran would welcome a mutually beneficial, fair, and equitable nuclear agreement.

Iranian officials have repeatedly warned that any potential US attack would not remain confined to Iranian territory, asserting that all US bases, military assets, and interests across the region would become legitimate targets. 

This raises a critical question: beyond US bases in the region, what might be the fate of the USS Abraham Lincoln—one of Washington’s most significant military assets—and how has Iran planned to respond to such a platform?

Swarm attack tactics

The general framework of Iran’s military defence policy is built upon a security conception centred on asymmetric strategy. 

This approach seeks to compensate for Iran’s structural limitations in conventional military capabilities by constructing a costly, uncertain, and deterrent defence architecture against technologically, economically, and militarily superior adversaries. 

Institutionalised through the constitution, long-term vision documents, and development plans, this understanding of defence is not confined to conventional battlefield engagement.

Rather, it is conceived as a comprehensive strategy aimed at prolonging the conflict, multiplying theatres of confrontation, and eroding the adversary's political and economic resilience. 

At the core of this asymmetric defence strategy lies the concept of deterrence.

Iran conceptualises deterrence not solely through conventional forces, but through a multilayered structure encompassing ballistic and cruise missiles, unmanned aerial vehicles (UAVs), cyber capabilities, and irregular warfare elements in the maritime domain. 

The doctrine of employing small, fast, and dispersed naval assets in the Persian Gulf and the Strait of Hormuz, missile capabilities capable of targeting regional military bases, and the potential for cyber retaliation against critical infrastructure together constitute the main pillars of this asymmetric deterrence posture. 

While enabling Iran to generate high strategic impact with limited resources, this structure is designed to raise the decision-making costs for adversaries in the event of conflict.

Another key dimension of Iran’s asymmetric defence doctrine is the integration of societal, ideological, and geographical factors into military strategy. 

Grassroots organisations such as the Basij provide a mobilisation model that extends defence beyond professional armed forces, while Iran’s mountainous and rugged terrain—combined with passive defence measures and underground infrastructure—enhances resilience against external attack. 

Within this framework, the ideological mission of the Islamic Revolutionary Guard Corps (IRGC) constitutes the institutional backbone of the asymmetric strategy, encompassing both internal security and external engagement. 

In other words, Iran’s defence policy deliberately distances itself from conventional power projection, instead articulating a distinctive defence model based on asymmetric engagement, protracted attrition, and multi-domain deterrence.

Within this overarching defence framework, swarm tactics occupy a distinctive and strategic position. 

The “swarm attack” approach, which Iran has uniquely adopted and operationalised, aims to neutralise enemy defences through irregular yet simultaneous and concentrated assaults. 

In this tactic, dozens or even hundreds of fast attack craft move in a synchronised manner toward enemy targets—such as aircraft carriers or large surface combatants—placing radar and air-defence systems under severe saturation stress. 

This enables a limited number of boats to approach within effective engagement range and activate their weapon systems.

The method typically relies on small groups of five to ten boats approaching the target from multiple directions to generate multi-axis pressure. 

The initial wave is intended to disperse the adversary’s attention and degrade defensive systems, while subsequent waves deliver the primary destructive strike. The effectiveness of this tactic is further enhanced at night or in maritime environments with low radar visibility. 

Owing to their low waterline profile and high speed, the boats can evade radar detection, while electronic jamming systems are used to disrupt enemy tracking and targeting.

This hit-and-run tactic is primarily executed by Iran’s small missile-armed vessels. 

After approaching a distance of approximately 30–40 kilometres from the target, these platforms launch cruise missiles and rapidly withdraw to avoid counterattacks. 

Such an approach significantly increases survivability for vessels with high manoeuvrability but limited armour and protection. Iran has permanently or semi-permanently deployed large numbers of fast attack craft across islands and coastal zones, dominating the Strait of Hormuz. 

These vessels can establish ambushes in areas of low radar visibility—such as narrow straits and coastal inlets around islands—and launch sudden attacks to exploit surprise and undermine the reflexive defensive responses of enemy ships.

Moreover, Iran’s naval tactics are increasingly characterised by a high degree of integration. Fast attack craft can coordinate real-time targets with UAVs, while targets identified by UAVs can be engaged in a coordinated manner by both coastal missile batteries and naval platforms. 

This integrated approach substantially enhances operational tempo and targeting accuracy. In the event of a potential US attack, it is widely anticipated that Iran would employ this tactic against the USS Abraham Lincoln aircraft carrier. The critical question, therefore, is what the institutional memory of the US Armed Forces suggests regarding such a scenario.

Millennium Challenge 2002 and Iran

Swarming tactics are a mode of attack in which numerous small, autonomous units simultaneously engage a target from multiple directions. 

Although such operations may appear amorphous or improvised at first glance, they in fact represent a deliberately planned and coordinated assault model. 

In practice, small, scattered, yet interconnected units function as a swarm, delivering swift, pulsed attacks that surround and saturate the target from all directions.

The origins of swarming are not confined to modern warfare. On the contrary, this approach is widely regarded as one of the oldest forms of combat practice in human history. 

In antiquity, nomadic and semi-nomadic societies often avoided direct, frontal confrontation with numerically superior and heavily equipped armies.

Instead, they sought to wear down their adversaries through sudden, multi-directional attacks, tactical withdrawals, and repeated raids. 

The Scythians, the Huns, and later Mongol cavalry formations exemplified early historical antecedents of swarming through decentralised manoeuvre, high mobility, and circular pressure applied around enemy formations. 

During these periods, swarming did not exist as a codified doctrine but rather as a battlefield reflex shaped by accumulated experience.

Within the institutional memory of the United States Armed Forces, the question of how effective such tactics might be in an Iran-related scenario was first systematically tested during the Millennium Challenge 2002 exercise. 

Conducted in the summer of 2002, Millennium Challenge 2002 was one of the largest and most expensive joint war games in US history, with an estimated cost of approximately $250 million. 

In the exercise, the Blue Force represented the United States, while the Red Force simulated a Middle Eastern adversary resembling Iran, though not officially designated as such. Command of the Red Force was assigned to retired US Marine Corps Lieutenant General Paul Van Riper.

Van Riper employed a range of asymmetric methods against a technologically superior opponent, including swarms of small boats, synchronised missile strikes, and low-technology or analogue communication systems such as motorcycle couriers and visual signalling. 

In the early phase of the simulation, these tactics inflicted severe losses on US naval forces, reportedly resulting in the sinking of multiple vessels, including an aircraft carrier. 

However, as the exercise progressed, its rules were modified: sunk ships were reintroduced into the scenario, and several of the Red Force’s operational options were restricted.

Van Riper openly objected to these changes and subsequently withdrew from the exercise.

The most enduring impact of Millennium Challenge 2002 lay not in the simulation's immediate outcomes, but in its influence on US strategic planning. 

The exercise accelerated a more serious engagement with asymmetric threats, including swarm attacks, anti-access/area-denial (A2/AD) strategies, and low-cost, high-impact operational concepts. 

Whether these lessons directly contributed to a US policy decision not to attack Iran in 2003 has never been definitively established. 

What does appear evident, however, is that more than two decades later, a strikingly similar scenario is now perceived as being contemplated—not in a simulated environment, but in the real world.