How does the GBU-53 differ from the GBU-39/B small diameter bomb?

• A. Can be used against moving targets.
• B. Has a larger warhead.
• C. Not GPS-guided.
• D. Is unguided.

Answer: (A)

Moving targets capability is the key differentiator. The GBU-53/B, known as Small Diameter Bomb II, uses multi-mode guidance that combines GPS/INS with imaging infrared and millimeter-wave radar seekers. This enables the weapon to identify, track, and continuously update its flight path to a moving target in real time, even in adverse conditions, and to hit vehicles or other mobile targets accurately. The GBU-39/B SDB I relies on GPS guidance and does not have a moving-target seeker, so it’s optimized for stationary or slowly changing targets. The other options aren’t the defining difference: the GBU-53 isn’t non-GPS-guided, it’s not unguided, and warhead size isn’t the distinguishing factor for this comparison.