Bunker-busting GBU-72 clearing hurdles in USAF testing

This article by Rachel S. Cohen was originally published by Military Times.

Air Force weapons testers are vetting a new 5,000-pound bomb that could become a bunker-busting tool against North Korean or Iranian nuclear facilities.

An F-15E Strike Eagle fighter jet with the 96th Test Wing at Eglin Air Force Base, Florida, wrapped up a slate of assessments Oct. 7 when it dropped a GBU-72 Advanced 5K Penetrator bomb from 35,000 feet over the installation’s vast test range, the service said in a release Tuesday.

The Air Force first tried loading, flying and releasing the weapon — which is a BLU-138 penetrator warhead combined with a modified Joint Direct Attack Munition GPS guidance kit and tail assembly — in July. The three-part series of tests aimed to prove whether the F-15E could safely fire the bomb guided by a JDAM tail kit used on a lighter, 2,000-pound bomb.

Related: The Air Force’s F-15E ‘bomb truck’ can now carry 15 JDAMS

Rather than letting a weapon rely on gravity to fall directly down onto a target, JDAM converts “dumb” bombs into GPS-guided munitions that can hit particular coordinates.

“In addition to the successful flight test series, the ground test series was Eglin’s largest-ever arena test, surpassing the previous titleholder by more than double,” the Air Force said. “The arena test, an open-air test where the warhead detonates surrounded by blast pressure sensors and fragment counting equipment, helps to determine the weapon’s lethality.”

The GBU-72 is designed to fly on fighter and bomber aircraft, though the Air Force hasn’t said which airframes could take on the new weapon other than the F-15E.

The Air Force has been researching the 5,000-pound weapon since at least 2017, and plans to begin buying them within the next year at a total cost of $36 million for 125 units, according to fiscal 2022 budget documents.

It’s smaller than other bunker-busters that have grabbed headlines in recent years, like the nearly 22,000-pound Massive Ordnance Air Blast bomb (or “Mother of All Bombs”) that hit an Islamic State cave and tunnel complex in Afghanistan in 2017, or the 30,000-pound Massive Ordnance Penetrator weapon.

Still, the bomb is expected to cause significantly more damage against hardened, deeply buried targets compared to the GBU-28, which the GBU-72 will replace, Program Manager James Culliton said in the release. GBU-28 is a 4,000-pound penetration bomb that was created for destroying underground Iraqi command centers in the 1990s, according to the Federation of American Scientists.

Rather than going after terror groups in Southwest Asia, the weapon joins a stockpile that can also be wielded against countries whose political and military ambitions are kept under close watch.

Related: This is what an F-35 looks like when it drops a nuclear bomb

“North Korea is one possible motivation — but underground nuclear production sites as much as bunkers, perhaps,” Michael O’Hanlon, foreign policy research director at the Brookings Institution, told Air Force Times. “Ditto in regard to Iran, another likely motivator.”

The new design boasts a smart electronic fuse that can activate at a preprogrammed location and be more durable and efficient — with fewer weapons needed to “achieve a kill” at lower cost — than other models, the Air Force said.

Air Force solicitations have indicated the service could eventually purchase as many as 2,000 of the bombs.

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Feature image: U.S. Air Force photo by Samuel King/ 96th Test Wing Public Affairs