Here's What You Need to Know: The U.S. Army is in a pinch.

Recent conflicts in Armenia, Iraq, Syria and Ukraine have demonstrated the widespread adoption of drones by state actors—as well as rebel and terrorist groups—for reconnaissance purposes and as improvised attack platforms carrying grenades or explosive charges. Most recently, Russian air-defense vehicles and electronic-warfare assets in Syria reportedly defeated a simultaneous rebel attack by thirteen kamikaze drones.

To counter such threats, ground forces needed fast-reacting Short-Range Air Defense systems, or SHORADS—and better yet, they need it come in a package that can move with frontline units on the battlefield, which the Army dubs “Maneuver SHORADS”.

For decades the U.S. military has counted on fighter jets to achieve air supremacy, and focused land-based defenses on long-range Patriot missiles as a counter to tactical ballistic missiles. But while long-range missiles and patrolling jet fighters may be able to engage a few drones at a time, both are impractical to employ against large numbers of tiny systems that might be dramatically cheaper than the missiles used to destroy them. In many cases, fighters and long-range SAMs will also simply be to far away to intervene against such small, low-flying threats in time, particularly if they are targeting frontline troops.

But this leaves the U.S. Army in a pinch—since 2004 it has drastically downsized its SHORADS force from twenty-six battalions in 2004 to just nine, only two of them active-duty, and phased out its last armored antiaircraft system, the M6 Linebacker.

The Linebacker was a Bradley Infantry Fighting Vehicle, a twenty-seven-ton heavily armed tracked troop carrier, with its TOW antitank missile launcher swapped out for a four-round Stinger missile system, with eight reloads in the hull. The heat-seeking FIM-92 Stinger became famous in the 1980s when the United States smuggled hundreds of the missiles to mujahideen insurgents in Afghanistan, who used them to cripple the Soviet Union’s helicopter-centric counterinsurgency campaign. The fire-and-forget missiles home in on the heat signature of an aircraft, and can strike targets up to three to five miles away while traveling over twice the speed of sound.

Placing the Stinger on an armored vehicle allowed it to accompany advancing mechanized and tank formations on offensive operations without exposing the launcher to small-arms and light-artillery fire. The Linebacker retained the Bradley’s twenty-five-millimeter autocannon for ground engagements, which has limited application against low-flying helicopters.

The M6 saw plenty of combat in Iraq. For example, Tip of the Spear: U.S. Army Small Unit Actions in Iraq describes an engagement in April 2004 in which a Linebacker platoon of the Fifth Air Defense Artillery Regiment sustained damage from a rocket-propelled grenade near Abu Ghraib while destroying suspected roadside IEDs. Later the same day, an M6 from the unit blew up a taxi that was ferrying insurgent RPG teams.

Obviously, actions such as these did not involve any engagements against aerial targets. Unlike today, cheap civilian drone technology simply wasn’t that prolific then. As a result, starting in 2005 the U.S. Army spent millions of dollars converting its Linebackers back to standard M2 Bradley models, retiring the M6 entirely.

This has left the AN/TWQ-1 Avenger Humvee as the only mobile SHORADS system maintained by the U.S. military. The Avenger mounts two four-round Stinger pods, as well as an M3P .50 caliber machine gun—a faster-firing type better optimized for antiaircraft use than the more common M2. Four hundred remain in service with the Army and Marine Corps out of an original force of two thousand.

However, a Humvee is obviously more vulnerable than an armored fighting vehicle—and the heat-seeking Stinger has much shorter-range than air-defense systems such as the Russian Pantsir-S, which has multiple radars and radio-directed missiles that can strike targets twelve miles away or further. Nor is the Stinger’s dual infrared/ultraviolet seeker optimal for taking out drones, which generate less heat than a helicopter or jet fighter.

Nonetheless, fifty Avengers have been rushed to reinforce NATO forces in Europe following reports of the wide-scale use of Russian drones in Ukraine to shut down sensors and communication systems and direct deadly artillery fires. Indeed, the Army recently tested an upgraded Stinger with a laser targeting system and proximity-fused warheads to help overcome the drone’s smaller heat signature.

Now the Army would like to regrow its Air Defense Artillery force to one battalion for each of its active-duty divisions, in addition to one battery attached to each of roughly thirty-one brigades—though whether funding for such a force exists is another matter. In January 2018, the service began training six hundred more Stinger teams for its light, mechanized and motorized infantry battalions. Presumably, many of them will have to dismount from their vehicles to fire.

Meanwhile, the Pentagon is testing a wide variety of new vehicle and short-range antiaircraft weapons to give it true Maneuver SHORADS capability. There are proposals install antiaircraft missiles on a range of new vehicles—including the Bradley. A new SHORAD Bradley upgrade offered by BAE would come with a new thermal sight, short-range AESA radar and drone jamming systems.

In addition to the Stinger, it could also employ a ground-launched version of the AIM-9X Sidewinder, a highly-maneuverable heat-seeking air-to-air missile, as well as radar-guided Hellfire antitank missiles repurposed for antiair engagements. These weapons could also be installed onboard Stryker eight-wheeled armored personnel carrier, or JLTVs, a successor to the Humvee. Earlier, the U.S. Army cut funding for the SLAMRAM, a Humvee mounting medium-range radar-guided AIM-120 missiles.

However, antiaircraft missiles may simply be too individually expensive to serve as a cost-efficient counter to cheap drones, which will likely be ubiquitous on a modern battlefield and could theoretically be dispatched in very large numbers in a swarm attack.

Thus, the military has tested out a wide-variety of laser and microwave weapons to literally burn drones out of the sky at almost no cost per “shot,” though most such weapons take several seconds to achieve a destructive effect, and may not be fast enough to destroy an incoming rocket or artillery projectile before it impacts. Still, a Stryker armed with a five-kilowatt laser successfully destroyed twenty-one out of twenty-three drones in an exercise in May 2017, so laser-armed Strykers and JLTVs are a distinct possibility. For now, though, it doesn’t seem that the Army has settled on a mobile direct-energy weapon system it is fully satisfied with.

Reintroducing rapid-fire radar-guided antiaircraft cannons like the M163, which mounted a Vulcan rotary cannon on an M113 APC, might be another means to close the cost-efficiency gap; air-bursting thirty-millimeter cannons and twenty-five-millimeter grenade launchers have been proposed with this application in mind. In any case, a proper antidrone system would also come with electronic-warfare systems to jam or even hijack the communication links connecting the drones to their handlers—the method reportedly used by Russian forces in Syria to disable six out of thirteen attacking drones.

The new age of drone warfare may mean that dominating the skies against manned aerial threats will no longer suffice to protect troops on the ground from the drone threat, even from adversaries with relatively limited resources to call upon. However, the capability gap is also a problem when facing more traditional threats from artillery and manned aircraft.

The Army and Marine Corps have relaxed on their short-range air defense capabilities since the end of the Cold War under the assumption that U.S. fighter jets would sweep enemy air power from the skies, as occurred in the 1991 Gulf War. However, a near-peer adversary’s air force may not be defeated immediately at the local level in the opening days of the conflict, leaving forward-deployed ground forces exposed. Furthermore, cruise missiles and rocket artillery are also proliferating around the world, and sufficiently agile short-range air defenses could help mitigate the damage inflicted by them if deployed both to accompany mobile frontline units and at key rear-area bases.

Sébastien Roblin holds a master’s degree in conflict resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.

This article first appeared in 2018.

Image: Wikimedia Commons