Secured to one of the four wing pylons of a Ukrainian Sukhoi Su-25M1 Grach (“Rook”; NATO reporting name Frogfoot) is a AASM 250 HAMMER ASM (Armement Air-Sol Modulaire 250 Highly Agile Modular Munition Extended Range Air-to-Surface Missile). More simply called Hammer, the AASM is a French designed, all-weather smart weapon which first entered service with both the French Air Force and Naval Aviation in 2007. The AASM is actually a kit which is fitted to existing free-fall bombs, turning them into guided missiles. The AASM kit can be fitted to 125, 250, 500, and 1,000 kilogram bombs (hence the number in the designation). France, as part of its military aid to Ukraine, has provided Ukraine with around fifty AASM systems per month in 2024.
The standard AASM (and likely the type provided to Ukraine) consists of a hybrid guidance system which combines a inertial navigation system (INS) with a global positioning system (GPS). This system is held within the finned nose-cap that is secured to the head of the bomb. The INS utilizes motion/rotation sensors whose input goes into a computer which constantly calculates the AASM's position, orientation, and speed. As such, it is essentially a fire-and-forget munition. However, the AASM can be fitted with a enhanced guidance suite which adds infrared homing. Without the infrared capability, the AASM can hit a target within 10 meters of the aim point. With the infrared homing, this improves to a single meter. A third option replaces the infrared homing with laser guidance system that permits on-target hits and can even allow the AASM to strike mobile targets. The second set of nose fins can rotate their angle, permitting the AASM to maneuver.
Attached to the back of the bomb body is a “range extension kit” which consists of a solid-fuel rocket motor and a “aerodynamic unit” consisting of four fins. When dropped at altitude, the AASM can achieve a maximum range of 43 miles but if dropped at low altitude, the range diminishes to a maximum of 9 miles.
Assuming the usage of a U.S. Mk. 82 250 kilogram bomb (which the AASM can be fitted to), the payload is usually 196 pounds (89 kilograms) of Tritonal explosive. This results in a blast radius of 80 meters by 30 meters with a lethal area stretching out to 2,400 square meters with fragments having speeds of between 1,700 to 5,458 miles per hour.
To date, in Ukrainian service, the Hammer is being launched from not only the Su-25 but also from Mikoyan MiG-29 fighters (NATO reporting name Fulcrum) using modified pylons.
