US Air Force seeks portable air defense guns

The US Air Force is seeking a new portable air-defense gun system to protect its overseas bases from drones and cruise missiles. This follows a series of Iranian attacks that killed US troops and damaged aircraft, including five KC-135 tankers on the ground.

The service published a Request for Information on Thursday for a Ground-Based, Medium-Caliber Gun Weapon System. The deadline for responses is October 9. The weapon must fire affordable munitions to provide persistent defense, with an initial focus on destroying subsonic cruise missiles and unmanned aircraft systems.

Iranian attacks prompt new requirement

Iran has conducted retaliatory strikes against US military installations across the Middle East. A one-way attack drone evaded defenses and struck a makeshift operations center at a civilian port in Kuwait, killing US troops. Further attacks killed more troops at Muwaffaq Salti Air Base in Jordan and Prince Sultan Air Base in Saudi Arabia. The strikes at Prince Sultan also damaged five KC-135 aircraft.

System requirements and parameters

The Air Force's RFI does not specify a caliber, but "medium-caliber" typically covers weapons from 20mm to 50mm. In a related development, the US Army published a notice in August for a 50mm anti-drone cannon and plans a live-fire test using Northrop Grumman's XM913 Bushmaster 50mm chain gun.

The new Air Force system must meet 15 baseline parameters. Key among these is its probability of kill against specific threats. It must also be capable of engaging Group 1 through Group 5 drones, which range from small models to very large unmanned aircraft flying above 18,000 feet.

Sensor integration and deployment

Contractors must carefully select organic sensor capabilities. The Air Force emphasized integrating the right mix of radar, electro-optical, infrared, or radio-frequency sensors. This ensures reliable target acquisition and tracking across varying weather, environments, and countermeasure scenarios.

The weapon must also have a lightweight, modular, and transportable design. It needs to be swiftly projected into austere theater environments to meet emergent threats.

The cost-per-engagement challenge

Based on the RFI, the Air Force is aware of a central challenge in modern air defense. Systems are often far more expensive than the drones and missiles they intercept, or they run out of ammunition before an attacker does. The new weapon must optimize munition performance versus cost.

The RFI stated the system must ensure "that the interceptor’s velocity, maneuverability, and terminal effects are maximized without driving the cost-per-engagement to unsustainable levels." Weapons will also be assessed for their range, elevation, and magazine capacity.