Should the F-35B stealth fighter squadron of the U.S. Marines in Japan fight a war against the People's Liberation Army Navy (PLAN) within this decade, it will do so without what's probably its most potent air-to-ground weapon -- the GBU-53/B Small Diameter Bomb II (SDB-II).

That's because the internal weapons bay of the stealth fighter can't carry a full load of eight SDB-IIs without extensive modification. That modification has been ongoing for the past several years and is expected to be completed by 2022.

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The Marines fly the F-35B, the short takeoff and vertical landing (STOVL) variant of the F-35. They plan to acquire 340 F-35Bs from the jet's maker, Lockheed Martin.

What makes the SDB-II the "super weapon" some analysts claim is to be is its smallness and smartness. Weighing just 130 kg (285 lb.), an SDB-II is only 1.8 meters long and 19 cm wide.

This small size means an F-35 can carry eight of these bombs instead of just two Mark 83 460 kg (1,000 lb.) bombs. And since the SDB-II is a smart weapon, that means it can attack eight targets instead of only two.

SDB II's smartness compared to the original version, SDB I, is because the former is armed with a tri-mode seeker.

This seeker allows each bomb to be steered towards its target using laser, imaging infrared or radar homing, or a combination of these modes. The tri-mode capability allows SDB-II to strike moving targets and stationary ones in any weather, day or night, at standoff ranges, with incredible precision.

Also aiding in SDB-II's accuracy is that it's a glide bomb sporting a pair of wings. The "DiamondBack" type wings deploy after release, increasing the glide time and the bomb's maximum range, which is 72 km against moving targets.

SDB-II has a circular error probable (CEP) of five to eight meters. Its high explosive warhead weighs 17 kg.

Because of its small size, hundreds of SDB-IIs can be carried by a single Northrop B-2 Spirit stealth bomber on a single mission. Each of these precision guided glide bombs can be programmed and networked together to hit separate targets in single or multiple target areas.

SDB II is expected to supplant the widely used JDAM (Joint Direct Attack Munition) bombs that are dumb bombs transformed into smart bombs by the addition of guidance kits. JDAMs have a range of 28 km and can range in weight from 227 kg to 907 kg.

TagsGBU-53/B Small Diameter Bomb II, SDB II, F-35B stealth fighter, People's Liberation Army Navy, Lockheed Martin, precision guided glide bomb