As the war with Iran enters its seventh month, its effects have reached deep into US strategic calculations. Decisions in Washington are increasingly being shaped not simply by what the United States is capable of striking, but by what it can afford to sustain as the conflict develops into an open-ended war of attrition.
Michael C. Horowitz, a former US Deputy Assistant Secretary of Defence for Force Development and Emerging Capabilities, examined this shift in an analysis published by Foreign Affairs under the title “How Iran Changed War: The Lessons of Tehran’s Use of Precise Mass”. Horowitz currently directs Perry World House at the University of Pennsylvania.
His central argument is that Iran and its armed forces have demonstrated how a militarily weaker state can obstruct, exhaust and impose substantial costs on far more powerful adversaries in modern warfare.
US and Israeli forces have struck thousands of targets across Iran, yet the Iranian state remains intact more than six months into the war.
Horowitz argues that the implications extend far beyond Iran. Powerful militaries, he says, are themselves likely to adopt offensive strategies built around what he calls “precise mass”, because defending against large quantities of inexpensive precision-guided weapons remains dramatically more expensive than launching them.
Surviving a Massive Bombing Campaign
Despite thousands of US and Israeli strikes, Horowitz argues that Iran may now be politically stronger than it was before the war.
Iran rapidly replaced senior officials who were killed, retaliated against Washington and its regional partners, and, according to Horowitz, succeeded in closing the Strait of Hormuz. The closure drove global energy prices higher while giving Tehran additional political leverage.
Horowitz attributes Iran’s ability to withstand the campaign to several factors.
Tehran had spent years preparing for the possibility of US and Israeli attacks, allowing the state to reconstitute its leadership after senior figures were killed.
Iran was also able to import enough goods to prevent its economy from collapsing completely despite the US naval blockade.
But one factor stands out in Horowitz’s analysis: Iran had accumulated a large arsenal of relatively cheap but accurate drones and missiles.
Those weapons gave Tehran the ability to launch effective counterattacks and, in Horowitz’s assessment, helped it close the Strait of Hormuz.
The Rise of “Precise Mass”
Horowitz describes Iran’s approach as part of a much broader transformation in warfare that he calls “precise mass”.
The concept refers to precision-guided weapons that are inexpensive enough to be manufactured and deployed in very large quantities.
Modern warfare, he argues, can no longer be dominated solely by militaries possessing small numbers of extraordinarily sophisticated weapons.
A weaker state may not be able to match a stronger adversary aircraft for aircraft, missile for missile or dollar for dollar. But it can increasingly compensate by launching large volumes of relatively inexpensive precision weapons.
That changes the economics of war.
The attacker can produce and launch drones and missiles at costs far below what the defender may need to spend intercepting them.
One of the clearest examples is Iran’s Shahed-136 attack drone. Horowitz places its cost at about US$35,000, compared with approximately US$4 million for a Patriot interceptor. The same cost disparity has also been documented by the Council on Foreign Relations.
A military cannot indefinitely rely on US$4 million missiles to destroy incoming weapons costing a fraction of that amount.
The defender may successfully intercept the attack and still lose strategically through financial and industrial exhaustion.
Advanced Weapons Still Matter
Horowitz does not argue that expensive military technology has become obsolete.
On the contrary, he says the Iran war has also demonstrated the continuing importance of advanced capabilities.
The United States was able to strike sensitive Iranian targets effectively, he argues, partly because it possesses artificial intelligence systems capable of identifying and recommending targets at unprecedented speed.
Sophisticated US weapons are also harder to intercept than cheaper alternatives and are more likely to destroy a target with a single strike.
The lesson, therefore, is not that cheap weapons have replaced advanced ones.
Rather, the emerging battlefield increasingly rewards militaries capable of combining sophisticated technology with large quantities of cheaper, expendable weapons.
Horowitz argues that the world is now learning from Iran what Ukraine had already begun to demonstrate: part of the future of warfare lies in producing and deploying large fleets of inexpensive weapons systems at scale. His broader work has similarly described “precise mass” as the ability to field low-cost precision weapons and sensors in large quantities.
Why Wealth Does Not Guarantee Military Adaptation
Horowitz also challenges the assumption that richer states automatically benefit first from every new military technology.
When a new weapons system is extremely expensive, wealthy powers generally possess a major advantage because they are best positioned to acquire it.
But when a military technology becomes cheap while requiring major organisational changes to use effectively, the advantage becomes less predictable.
Smaller or less wealthy states may adopt the technology just as quickly, or even faster.
This creates a structural challenge for militaries such as that of the United States, which have traditionally been organised around relatively limited quantities of highly sophisticated, extremely expensive and difficult-to-produce weapons.
Tomahawk missiles and F-35 fighter aircraft represent that model.
“Precise mass” requires something different.
It requires large production volumes, different training systems, new operational concepts and a willingness to treat some weapons as expendable rather than scarce strategic assets.
Iran Turned Its Limitations Into an Advantage
Iran’s military development illustrates the point.
Because Tehran was denied access to many advanced military technologies, it invested heavily in long-range one-way attack systems and comparatively inexpensive ballistic missiles.
That limitation forced Iran towards weapons that could be produced and launched in much greater numbers.
According to Horowitz, this enabled Tehran to fire inexpensive drones and missiles at a rapid pace against US bases and infrastructure across the region.
The United States, meanwhile, inflicted billions of dollars in damage on Iran but was forced to consume valuable stocks of Tomahawk missiles, SM-6 interceptors and other costly weapons.
Washington now faces the additional burden of replenishing not only its own inventories but also stocks required by partners including Taiwan and Ukraine.
The problem therefore extends beyond the immediate battlefield.
Every expensive missile consumed in one theatre is a weapon that must be manufactured again before it can be available elsewhere.
A Warning for Washington
Horowitz argues that Washington needs to absorb the lesson quickly.
Reliance on sophisticated, expensive and slow-to-produce weapons is no longer sufficient either to prevail in major wars or to protect US allies and partners.
This is particularly important as the Iran war consumes missile inventories that Washington also considers necessary for deterring China and responding to other potential conflicts.
Horowitz argues that the United States should therefore rapidly expand production of its own “precise mass” weapons while investing heavily in inexpensive defensive systems capable of intercepting cheap drones and missiles without imposing an unsustainable cost on the defender.
The US military would also need to restructure parts of its organisation, training and operational doctrine to use those systems effectively.
Even then, Horowitz argues that technological and industrial changes alone will not be enough.
Meaningful reform will require capable military commanders and senior civilian officials who remain in their positions long enough to implement major institutional changes, something made more difficult by rapid turnover within Pentagon leadership.
Iran’s experience has therefore exposed a larger problem for the world’s most heavily armed militaries: technological superiority remains powerful, but it no longer guarantees favourable economics on the battlefield.
A state that cannot match the United States in conventional military spending may still be able to force it into an expensive contest of endurance, using weapons cheap enough to replace far faster than the systems designed to destroy them.
