The U.S. Air Force is seeking anti-aircraft gun system to help defend its air bases around the world from drones and cruise missiles. The Request for Information (RFI) about these systems, posted on the government’s contracting website on Thursday, is part of a larger Air Force effort to play a greater role in air base defense via ground-based air defenses (GBADs), a capacity traditionally performed by the Army. As a result, the Air Force currently has no such systems. Now it is interested in changing that.
The request comes as the war against Iran exposed gaps in how the U.S. can provide effective, sustained air defenses for its foreign installations and amid concerns about a future fight against a peer competitor like China or Russia.
“The Government is conducting market research to identify potential industry sources capable of providing solutions for a Ground-Based, Medium-Caliber Gun Weapon System that fires affordable munitions, enables defense against air and missile threats with an initial focus on subsonic cruise missiles (CM) and Unmanned Aircraft Systems (UAS) to provide persistent defense in support of [the] United States Air Force,” the RFI notes.
The RFI doesn’t stipulate what it considers a medium-caliber round; however, according to the Army, the list includes 20mm, 25mm, 30x113mm, 30x173mm and 40mm shells.
“To effectively assess and compare air defense weapon system performance, there are 15 critical baseline operational and technical parameters that must be analyzed in unison,” the RFI explains.
“These key metrics begin with the system’s Salvo Probability of Kill (Pk) evaluated against both Cruise Missiles (CM) and Unmanned Aircraft Systems (UAS) Groups 1-5 at maximum range and altitude, ensuring robust lethality against diverse modern threats,” the RFI notes.
A salvo probability of kill measures how effectively a salvo, as opposed to a single shot, defeats a target.
The following chart displays the weight, normal operating altitude and speed of the five drone group classifications.
The Air Force wants this system to be “rapidly deployable, maintaining a lightweight, modular, and transportable footprint that can be swiftly projected into austere theater environments to meet emergent threats.” The RFI does not provide further details of how the Air Force is looking to transport these systems; however, the service relies on its fleets of C-130 Hercules, C-17 Globemaster III and C-5 Galaxy transport aircraft to move equipment. The size and weight of the systems determines which kind of aircraft can transport it.
These systems could also be moved by truck or ship or on their own if self-propelled, but those options also incur a cost in terms of the timeliness of delivery, and can be impossible for rapid global deployments.
A key point of evaluation will be the overall cost of the munitions. The Air Force wants to ensure that the shell’s velocity and terminal effects “are maximized without driving the cost-per-engagement to unsustainable levels or exceeding the physical constraints of the host platform,” the RFI states. We’ll discuss these factors in more detail later in this story.
The service is also looking for the integration of “the right mix of radar, electro-optical, infrared, or radio-frequency sensors—to ensure reliable target acquisition and tracking across varying weather conditions, environments, and countermeasure scenarios.”
As we noted at the top of this story, the Air Force is seeking to improve its organic ability to defend its bases. This has become “an increasingly high priority” for the service, Air Force Secretary Troy E. Meink told Congress on May 20.
“The Air Force is developing organic air and missile defense capabilities, including Counter-small Unmanned Aircraft Systems (C-sUAS) to defend our air bases in all theatres [sic],” Meink stated in his written testimony. “The fielding of the Air Base Air Defense Systems (ABADS) missile defense capability, including kinetic defenses, at overseas main operation bases contributes to joint layered defense but does not reduce the need for increased joint investment in air and missile defense. We will continue to work judiciously for the development and procurement of these critical defensive capabilities.”
In its Fiscal Year 2027 budget request, the Air Force is seeking about $1.4 billion for a missile defense variant of the Air Base Air Defense Systems (ABADS), according to Air & Space Forces Magazine. In addition, the Air Force also requested $51.8 million in procurement funds for its Small Unmanned Air Defense Systems (SUADS) in Fiscal Year 2026, according to the Air Force Fiscal Year 2026 budget justification book.
The war against Iran and the Ukraine war have, in particular, illustrated the challenges of defending against drones and cruise missiles.
Iran launched thousands of these weapons against U.S. air bases and a wide range of critical infrastructure targets in Bahrain, Israel, Iraq, Jordan, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates. It also launched hundreds of ballistic missiles.
Taken in concert, these attacks have resulted in the deaths of at least nine U.S. troops, more than 760 injuries and the destruction of aircraft, radars and other critical equipment as well as widespread damage to the Middle Eastern nations Iran has targeted.
Concerns about the tremendous expenditure of U.S. interceptors exacerbating the stress on America’s magazine depth of these high-end defensive weapons are an issue that TWZ has raised frequently for years.
There are two facets to potential use of gun systems for base defense. The first is that in complex air defense environments, it provides an inner, last line of defense against incoming threats. If the outer layers fail to take down the target or that target is not considered a priority over others, a hard-kill gun system offers a predictable and relatively reliable fallback. The gun system would become even more important if interceptor stocks run low, even temporarily, and those weapons need to be rationed for higher-end threats. With the outer defensive rings collapsing, the inner becomes far more important.
For small drones, that interceptors would not be effective anyway, the gun system can take them down in localized air defense scenarios. Then there is also defending bases in lower threat areas where there are not additional layers of SAM systems. A gun system can provide a core aerial defense against lower-end, lower-density drone and cruise missile threats without costing huge sums of money or requiring a huge logistical footprint.
Beyond that, there is a direct cost comparison argument, but again, that is in a vacuum and a gun system cannot take the place of a multi-layered air defense system without inviting huge risk. Still, the engagement cost comparison is worth mentioning.
High-end, expensive, difficult-to-manufacture air defense weapons, like Patriot PAC-3 MSE, are clearly inefficient against drones. For instance, a mass-produced Iranian Shahed-136 can cost about $35,000 to $50,000, while a Patriot PAC-3 can run about $5 million and takes years to procure. By comparison, the cost-per-engagement efficiency of gun-based air defense systems, designed to defend against drones and subsonic cruise missiles, is far greater. One example of how this plays out is the cost of firing the Army’s Centurion Counter-Rocket, Artillery, Mortar (C-RAM) system. It is a ground-based version of the Phalanx Close-In Weapon System (CIWS) used on various U.S. and foreign warships, and is armed with a six-barrel 20mm Vulcan Gatling-type cannon firing M940 rounds. Those self-destructing rounds currently have a price tag of $80.70, according to the Army’s Fiscal Year 2025 budget request. This means a two-second burst from a Centurion, at a rate of fire of 4,500 rounds per minute, would cost just over $12,100.
Again, this is not a strict apples-to-apples comparison, but it can become a bigger factor during prolonged conflicts when high-end weapons stocks begin to run short. It’s also worth noting that drone interceptors are a rapidly growing capability set that are a lower-cost option for swatting down one-way attack drones and even some cruise missiles. Systems like Coyote have been in service for years with the Pentagon and have been protecting bases overseas with strong results. Even cheaper systems are emerging out of lessons learned in Ukraine. All of these systems have their own advantages and disadvantages, but pairing them with a new gun system would likely have synergistic effects. Overall, deploying densely layered short-range air defenses is becoming increasingly important in its own right, at least in high-threat areas.
Ukraine has a great deal of experience with the costs and prioritization of air defense capabilities. The country faces daily attacks by Russian missiles and drones, which is causing mounting casualties and destruction. This ceaseless bombardment has almost completely depleted Ukraine’s supply of Patriot interceptors, leaving it largely defenseless against ballistic missiles. As we noted yesterday, Ukraine is also running short of air-to-air missiles its Air Force F-16s use to swat down drones.
However, Ukraine has also relied heavily on a wide array of gun-based air defense systems, including the German-made Gepard self-propelled anti-aircraft guns (SPAAG). Based on the chassis of the Leopard 1 main battle tank, Gepards feature twin radar-aimed 35mm automatic cannons, mounted on a single turret. The German variant sports an S-band search radar and a Ku-band tracking radar. These radars are critical to the Gepard’s ability to locate, track, and engage targets at night and amid poor weather conditions.
The success of the Gepards in Ukraine have helped spur new global interest in SPAAGs.
The following video shows a Gepard blasting an Iranian-made Shahed-136 out of the sky.
The Air Force force is also looking at directed energy weapons like lasers for force protection and especially for defending bases overseas. While gaining traction across the services due in large measure to the much lower cost of delivering effects, these systems are still works in progress. Gun-based air defenses, on the other hand, are mature and proven and modern precision-guided, programable ammunition makes them even more efficient and effective.
Beyond the cost, high-end air defense systems — including their component sensors — though portable, are generally fixed to a specific location. That makes them vulnerable to attack. This has been the case in both the war against Iran and Ukraine. The same concerns hold true of aircraft. Both conflicts have shown aircraft vulnerability to drones when parked out in the open. Ukraine’s Operation Spider Web attack on Russian strategic bombers last year in particular shed light on this issue, which we have been sounding the alarm a long time.
For years now, U.S. military officials have often pushed back on the utility and cost-effectiveness of investing more in the physical hardening of bases and other critical facilities, especially shelters to shield aircraft from drones and other threats. However, that is beginning to change. In February, the Pentagon released new guidance about hardening, which “does not mean enclosing an entire facility, but selectively introducing obstacles that disrupt predictable aerial access,” the document explains. “Even modest obstacles can deter low-cost, consumer-grade drones and force higher-risk flight profiles.”
In addition to these challenges, the Air Force is also facing the headwinds of an overall lack of U.S. short-range air defense capabilities, a concern we have been highlighting for years. Currently, there are three gun-based SHORAD systems being fielded by the U.S. military. These include the aforementioned Centurion C-RAM systems.
The Army also uses the Sgt. Stout, an air defense system based on the 8×8 Stryker light armored vehicle. The Sgt. Stout has a turret that can be fitted with up to two four-round launchers for Stingers. Those launchers can also be swapped out for ones that can be loaded with a pair of millimeter-wave radar-guided AGM-114L Hellfire missiles. The turret also has a 30mm XM914 automatic cannon, which can fire proximity-fuzed airbursting rounds against drones and other aerial threats, and a 7.62x51mm M240B machine gun.
(U.S. Army photo by Cpl. Emaney Wilson) Cpl. Emaney Wilson
The Marine Air Defense Integrated System (MADIS) is armed with 30mm cannons and M240C coaxial machine guns in remote weapon stations (RWS). The RWS on one of the two vehicles is also configured to fire Stinger missiles for a spectrum of ground-based air defense scenarios.
The Army may have additional gun-based systems on the way. In July, the service put out a request for information to companies that can provide a new gun-based air defense option, using a 50mm cannon system to track and defeat Group 1, 2 and 3 drones.
A few weeks later, Northrop Grumman introduced its Raid Hunter 50mm GBAD system, which it said “combines proven Chain Gun® technology, precision‑guided 50mm ammunition and a networked, interoperable system controller to deliver powerful protection against high-volume, mixed-threat aerial raids. It is designed to defeat a range of aerial threats including high‑priority cruise missile threats, unmanned aerial systems (UAS), and other advanced threats.”
There are foreign options should the Air Force want to go that route. For instance, German arms maker Rheinmetall makes the popular Skyranger 35 gun system, which is a turret that can fit on a wide array of armor hulls.
The Skyranger 35 “is equipped with a KDG 35/1000 revolver cannon in 35 mm x 228 caliber with a firing rate of 1,000 rounds per minute,” according to Rheinmetall, which began delivering these to Ukraine in January. “It has an effective range of up to 4,000 meters and a high degree of commonality with the Oerlikon Revolver Gun Mk 3. Thanks to AHEAD technology, the Skyranger 35 is airburst-capable. In the future, it will also be possible to equip it with modern guided missiles.”
Skyranger 35s mounted on Cold War-era Leopard 1 tanks have just emerged on the battlefield for Ukraine.
You can see a video of that system below.
Skyshield is the fixed placement cousin of this system and has been bought by a number of nations
This is just one example of a large number of potential offerings that could fit the USAF’s interests, from both domestic and foreign origins.
As we discussed earlier in this story, the U.S. is already facing a challenge defending against Iranian threats. A war with China would be more devastating and, when it comes to the Air Force protecting its bases, require far more robust defenses. At the same time, the Air Force is still very early in the process of taking on more responsibility for protecting its assets.
Parties have until 5 p.m. Oct. 9 to submit their proposals to the Air Force for a gun-based air defense system. With limited options and the service pushing to address its growing desire for organic air defenses, it will be interesting to see who comes forward and what systems they offer. We will provide more details about this effort when they become available.
Contact the author: howard@twz.com
Loading comments…
Comments couldn’t be loaded. Please refresh the page.