Amid tensions, a U.S. bomb designed to hit targets such as Iran’s underground nuclear facilities briefly reappears

DUBAI, United Arab Emirates — As tensions with Iran escalated over its nuclear program, the US military this month released images of a massive bomb designed to penetrate deep into the earth and destroy underground facilities used to enrich uranium.

The U.S. Air Force released rare images of the GBU-57 weapon known as the “Massive Ordnance Penetrator” on May 2. Then he took down the pictures—apparently because the photographs revealed sensitive details about the weapon’s composition and impact.

The release of the photos comes as the Associated Press reports that Iran is making steady progress in building a nuclear facility that is likely beyond the range of the GBU-57, the US military’s last-ditch weapon for taking out underground bunkers.

WHAT DO WE KNOW ABOUT AMERICA’S MASSIVE ORDNANCE PENETRATOR?

The US developed the Massive Ordnance Penetrator in the 2000s as concerns grew that Iran was building nuclear facilities underground.

The Air Force posted pictures of the bombs on its Facebook page at Whiteman Air Force Base in Missouri. The base is home to a fleet of B-2 stealth bombers, the only aircraft capable of dropping the bomb.

In the caption, the base said it received two Massive Ordnance Penetrator bombs for a squadron to “test their performance”.

It’s not the first time the Air Force has released photos and videos of the bomb, which coincided with growing rifts with Tehran over its nuclear program. In 2019, the US military released a video of a B-2 bomber dropping two bombs. The Air Force did not respond to requests for comment on why it posted — and removed — the latest set of photos.

WHAT DID WE LEARN FROM THE PHOTOS?

In the most recent photos, the bombs were listed as weighing 12,300 kilograms (27,125 pounds). The bomb was also described as carrying a mixture of AFX-757, a standard explosive, and PBXN-114, a relatively new explosive, said Rahul Udoshi, senior weapons analyst at Janes, an open-source intelligence firm.

The bomb’s mass, judging from the stenciling, shows that much of it comes from its thick steel frame, which allows it to chew through concrete and soil before detonating. However, it remains unclear what the exact effectiveness of the weapon would be.

The publication of the photos was first reported by the Internet news site Warzone. The AP reached out to Whiteman Air Force Base and the Air Force Global Strike Command with questions about the images. Within a day, the Facebook post disappeared.

According to Udoshi, the Air Force probably took them down because they revealed too much information about the bombs. “Immediate removal from the Internet without comment (or justification) means that there is a bug,” Udoshi said.

WHAT ROLE DOES THIS BOMB PLAY IN THE POTENTIAL GOAL OF IRAN’S NUCLEAR PROGRAM?

The AP reported Monday that Planet Labs PBC satellite images show that Tehran is digging tunnels in a mountain near the Natanz nuclear power plant in central Iran. Excavation mounds at the site suggest the facility could be between 80 meters (260 feet) and 100 meters (328 feet) underground, according to an analysis by experts and the AP.

Experts say the size of the construction project indicates that Iran would likely be able to use the underground facility for uranium enrichment — not just centrifuges. The tubular centrifuges, arranged in large cascades of dozens of machines, rapidly spin the uranium gas to enrich it. Additional machines would allow Iran to rapidly enrich uranium under the protection of the mountain.

That could pose a problem for the GBU-57: In a previous description of the bomb’s capabilities, the Air Force said it could penetrate 60 meters (200 feet) of soil and cement before detonating.

CAN THE UNITED STATES STILL TRY TO DROP THE BOMB?

US officials have talked about using two such bombs back-to-back to ensure the site is destroyed. But the new depth of the Natanz tunnels still poses a serious challenge.

Further complicating possible US military strikes is that the B-2 has been grounded for months since December when one of them caught fire after an emergency landing. On Monday, Gen. Thomas A. Bussiere, commander of the Air Force’s Global Strike Command, announced that the B-2 landing had been cleared.

“While the B-2 fleet’s security pause is officially over, our ability to deliver nuclear deterrence and long-range strike capability has never been in doubt,” the Air Force said in a statement.

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Follow Jon Gambrell on Twitter at www.twitter.com/jongambrellAP.

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