For thirty years the United States Air Force has fought wars in which nothing much threatened its airfields. Aircraft were parked in neat rows in the open because nobody could reach them.
That assumption is gone. And the Air Force’s response is to go looking for something it largely gave up decades ago: anti-aircraft guns.
On 3 September 2026 it published a request for information for a Ground-Based, Medium-Caliber Gun Weapon System. Responses are due by 9 October.
Quick Facts
What it is: a U.S. Air Force request for information for a Ground-Based, Medium-Caliber Gun Weapon System
Published: 3 September 2026, on SAM.gov. Responses due 9 October 2026
Targets: initially subsonic cruise missiles and uncrewed aircraft, from Group 1 through Group 5 — hand-launched quadcopters up to large drones operating above 18,000 ft
Calibre: not specified. “Medium-calibre” conventionally means roughly 20 mm to 50 mm
Assessment criteria: 15 baseline parameters, including probability of kill, range, elevation, magazine capacity, crew size, sensor integration and the ability to defeat saturation attacks
Deployability: the RFI asks for a lightweight, modular, transportable system that can be moved quickly into austere locations
Parallel effort: in August 2026 the U.S. Army issued a sources-sought notice for a 50 mm anti-drone cannon, with live fire planned using Northrop Grumman’s XM913 Bushmaster
Why now: Iranian strikes on U.S. installations in the Middle East, which killed American personnel and, according to a congressional report, left 42 U.S. aircraft lost or damaged during Operation Epic Fury
The arithmetic that broke air defence
The problem is not that American air defences do not work. It is that they are economically unsustainable against the thing now being thrown at them.
A Patriot interceptor costs millions of dollars. A one-way attack drone can cost tens of thousands, sometimes less. Trading the first for the second is a victory on the day and a defeat over a campaign, because the attacker can build faster than the defender can restock.
The RFI is unusually blunt about this being the design constraint rather than an afterthought.
A gun fixes the arithmetic. A 35 mm round costs a few hundred dollars rather than a few million, and a magazine holds a great many of them. Against a saturation attack, the side with more shots wins, and guns have far more shots.
This is not a new idea, it is a returning one
The United States already knows guns work for this. The Centurion C-RAM — a naval Phalanx close-in weapon system mounted on a trailer — went to Iraq in late 2006 to protect the Green Zone, where its six rotating 20 mm barrels became one of the defining sounds of the war.
What has changed is the target set. C-RAM was built to catch rockets and mortar bombs on short, predictable ballistic arcs. A cruise missile flies a powered profile and manoeuvres; a drone loiters, approaches from an unexpected bearing, and may arrive with forty friends. That demands more range and a heavier, smarter projectile than 20 mm delivers.
Which is why the calibre bracket matters. European systems have already converged on this answer: Rheinmetall’s Skyranger 35 uses a 35 mm revolver cannon firing programmable airburst ammunition that detonates near the target and throws a cloud of tungsten sub-projectiles — reportedly 152 of them per round — into its path. You do not need to hit a drone. You need to put metal where it is going.
The Centurion C-RAM, the land-based Phalanx that has been doing this job since 2006.
The sensors are the hard part
Guns are the easy half. Finding a small, slow, low-flying object against ground clutter, classifying it correctly and tracking it accurately enough to put a burst in front of it is the genuinely difficult engineering, and the RFI puts the burden squarely on bidders.
The word doing the work there is “organic”. The Air Force wants a system that brings its own eyes, rather than one that depends on being plugged into a larger air defence network that may not exist at a dispersal field. That is a direct consequence of Agile Combat Employment: if the plan is to scatter aircraft across many small locations, each location needs its own protection.
Why stopping large numbers of cheap drones is as much a sensing and electronic problem as a shooting one.
A demonstration of the radar and electronic-warfare side of the problem: finding and tracking the target is what decides whether the gun ever gets a useful shot.
An RFI is not a programme
It is worth keeping expectations calibrated. A request for information is the Air Force asking industry what exists and what it would cost. It is not a competition, not a contract and not a budget line, and plenty of RFIs lead nowhere.
What makes this one credible is that the demand signal is not theoretical. Aircraft have been damaged on the ground, personnel have been killed, and the Army is running a parallel effort at 50 mm. When two services independently reach for the same answer in the same season, something has changed in how the Pentagon expects the next fight to look.
For an air force that has spent a generation treating its own runways as sanctuary, that is the uncomfortable part. The guns are coming back because the sanctuary is gone.
Sources: U.S. Air Force request for information published on SAM.gov, Military Times, Air & Space Forces Magazine, Army Recognition, Northrop Grumman, Rheinmetall, congressional reporting on Operation Epic Fury.
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