US military faces challenges in sustaining long war in Iran

Questions over US staying power

As tensions with Iran simmer, a critical question emerges: can the US military sustain a prolonged conflict? Analysts point out that while the US possesses overwhelming firepower, a long war demands more than just bombs and missiles. It requires a steady supply chain, troop rotation, and political will—all of which face strain.

The Pentagon has not publicly outlined war plans for Iran. But military experts say a campaign against Iran would be unlike the short, decisive strikes seen in recent decades. Iran's geography, military doctrine, and regional alliances could stretch US capabilities thin.

Logistical hurdles in a vast theatre

Iran spans over 1.6 million square kilometres, with rugged mountains and vast deserts. Targeting its nuclear facilities, missile sites, and naval assets would require sustained air operations. The US Air Force would need to fly hundreds of sorties daily from bases in the Gulf, Qatar, and Diego Garcia.

Fuel, munitions, and spare parts must flow continuously. A 2002 RAND study estimated that a major theatre war could consume 20,000 tonnes of supplies per day. For Iran, that figure could be higher. The US military has pre-positioned stocks in the region, but these are finite. Replenishment would depend on sea lines of communication that Iran could threaten with mines, submarines, and anti-ship missiles.

Manpower and rotation pressures

Sustaining a long war also means deploying tens of thousands of troops. The US military, already stretched by commitments in Europe and the Indo-Pacific, would face rotation challenges. Extended deployments strain morale and readiness. The Army and Marine Corps have reduced end strength since the Afghanistan withdrawal.

Reserve and National Guard units would likely be mobilised. But calling up reserves for a lengthy campaign carries political risks at home. Congress would need to authorise additional funding, and public support could waver as casualties mount.

Iran's asymmetric response

Iran is not a conventional foe. It has invested heavily in proxy forces across the region—in Iraq, Syria, Yemen, and Lebanon. In a war, these militias could attack US bases, diplomats, and allies simultaneously. Such a multi-front conflict would force the US to divert resources from the main effort.

Iran also possesses a large arsenal of ballistic missiles and drones. Its coastal defence systems and fast attack craft could threaten US Navy vessels in the narrow Strait of Hormuz. A prolonged blockade or mine-clearing operation would tie up naval assets for months.

Historical lessons from Iraq and Afghanistan

The US learned hard lessons from its long wars in the Middle East. The 2003 invasion of Iraq led to a decade-long insurgency that cost over 4,400 US lives and trillions of dollars. Afghanistan proved even more costly. In both cases, the initial military victory gave way to protracted, grinding conflicts.

Analysts warn that a war with Iran could follow a similar pattern. The US can win battles but may struggle to win a war of attrition. Iran's population of 85 million and its history of resilience during the Iran-Iraq war suggest it could absorb heavy punishment and continue fighting.

Political and diplomatic dimensions

A long war also depends on domestic political support. US presidents have limited appetite for another major Middle Eastern conflict. The Biden administration, like its predecessors, has favoured diplomacy and sanctions over military action. Any prolonged campaign would require clear objectives and an exit strategy—neither of which is easy to define against Iran.

Allies in the region, such as Saudi Arabia and the UAE, would be cautious about openly supporting a US war. Their own vulnerability to Iranian retaliation could limit basing and overflight permissions. Meanwhile, China and Russia would likely oppose US action diplomatically, complicating UN Security Council approval.

As the debate continues, the question remains unanswered. US military planners are gaming out scenarios, but the final answer may depend on factors beyond the battlefield: political resolve, allied cooperation, and Iran's own strategic choices.