Heat-seeking missiles, easily manufactured by Iran using Cold War-era technology, pose an asymmetric threat. Their passive guidance prevents electronic warning, while saturation and ambush tactics have downed F-15Es and damaged F-35s, imposing high costs on US low-altitude air operations.
The missiles are cheap to make, easy to use, and deadly for low-level US aircraft caught unawares.
In modern conflicts, aircraft are increasingly threatened by ground fire, even against less advanced militaries and non-state militias. Indeed, the United States has already lost several dozen aircraft and unmanned drones against Iran during Operation Epic Fury—most notably an F-15E Strike Eagle downed over Iran two weeks ago, with the pilot and weapons systems officer later rescued from the ground.
How is it that countries like Iran can field effective air defense systems against far stronger ones like the United States? The answer lies in large part with anti-air missiles, which rely on technology that is decades old, widely proliferated, and easy to manufacture even by pariah states like Iran.
How Do Anti-Air Missiles Work?
There are three basic types of anti-air missile.
First, infrared (IR)/heat-seeking missiles target an engine’s heat signature. An example of a heatseeking missile is a MANPADS, a relatively low-cost and low-tech shoulder-fired missile that can be seen in recent footage almost taking down a US F/A-18 Super Hornet.
Second, radar-guided missiles use ground or onboard radar to close on a target. These missiles are more advanced and somewhat harder to make.
Third, command-guided missiles are missiles that are guided by a human operator while in flight. Unlike the first two systems—which are “fire and forget”—these require the highest degree of operator skill to use effectively. However, they can also be the most effective, as they rely on sight and cannot be fooled by stealth technology; no technology yet exists to make a plane invisible to the naked eye.
With multiple guidance methods, anti-air missiles as a weapon class today typically employ more than one type of guidance, reducing their reliance on any single technology and making it harder for a modern stealth plane to evade them.
How Heat-Seeking Missiles Became a Gamechanger for Iran
Heat-seeking missiles are especially interesting because systems like the have been used so effectively, and provided such asymmetric advantage, in Operation Epic Fury.
Heat-seeking anti-air missiles detect an aircraft’s engines, which emit infrared radiation. The missile seeker detects the heat contrast between the engine and the surrounding, relatively cool air. The missile’s seeker locks on to the strongest IR source—most often the aircraft’s engine—and then tracks the heat source, adjusting its flight path continuously. And while early systems relied on relatively simple IR sensors, modern heat-seeking missiles rely on imaging infrared (IR), making it harder for a pilot to trick them with countermeasures such as flares. A proximity fuze detonates near the target, meaning that the missile does not need to physically hit the aircraft to go off—only come close enough to cause significant damage when it explodes. Even a near miss, such as the near-shootdown of a US Air Force F-35 by an Iranian heat-seeker in mid-March, can cause major damage to a targeted aircraft.
Heat-seekers are effective because they are passive, meaning they do not emit radar emissions of their own. A plane can detect when an enemy has “locked on” with radar and can take evasive action, but a pilot often has no idea that a heat-seeking missile is inbound until it is far too late. Heat-seekers are also highly mobile, often from shoulder-fired systems that cost drastically less than the aircraft itself. These heat-seekers are also simple, with fewer components than radar systems.
Simple heat-seeking missiles such as MANPADS tend to work best at low altitudes, particularly given their range constraints. This gives higher-altitude aircraft a measure of protection against them—though not immunity, as the F-35’s brush with disaster shows. However, low-flying aircraft such as ground attack aircraft, helicopters, and unmanned drones are all particularly vulnerable.
In short, heat-seekers are a cheap option for poor militaries or non-state militia groups, but can still impose a high cost on adversaries—who must adjust their war planning to accommodate such an effective weapon system.
Iran Has No Shortage of Heat-Seeking Missiles
A country like Iran has no problem building heat-seeking anti-air missiles because the technology is mature, having come of age during the Cold War and having since proliferated widely. Iran has thousands of Soviet and Russian systems in its arsenal, and can easily reverse-engineer them. These relatively simple systems feature modular components—seeker, propulsion, and warhead—that make production easier. And because they do not require cutting-edge industrial capabilities like advanced computer chips, they are industrially feasible for a country like Iran to produce domestically rather than smuggle in.
Tactically, these heat-seekers are legitimate, creating a low-altitude threat for strafing aircraft and helicopters. MANPAD users can use ambush tactics with great effect, launching from hidden positions. And because the systems are cheap and readily available, saturation tactics are feasible, allowing for multiple simultaneous launches that can overwhelm defenses. Indeed, the heat-seeking missile is most dangerous when aircraft operate low and slow, imposing significant costs against aircraft engaging with ground targets.