In one of the most direct strikes on Iran’s nuclear programme to date, the United States deployed six GBU-57 bunker-buster bombs on 22 June. These massive bombs were dropped by B-2 Spirit stealth bombers from over 13,000 km away. The primary target was Fordow, a hardened underground site believed to hold Iran's most advanced uranium enrichment operations.
"Obliteration is an accurate term!" US President Donald Trump declared after the strike. He later added, "A regime change will Make Iran Great Again," but US officials insisted that ' Operation Midnight Hammer' was not designed to overthrow Tehran.
The US also launched 30 Tomahawk cruise missiles at sites in Natanz and Isfahan. Satellite images from Maxar Technologies showed long lines of vehicles outside Fordow two days before the attack, suggesting Tehran had moved much of its 60% highly enriched uranium in advance. A senior Iranian source confirmed to Reuters that this stockpile was relocated to an undisclosed location.
Read more on the Israel-Iran ceasefire here
The return of the Bunker Buster
This wasn’t the first time America used bunker-busting bombs to alter the course of a conflict. During Operation Desert Storm in 1991, the US rushed to develop a weapon that could punch through 50 feet of reinforced concrete. The GBU-28 was built in just three weeks.
Saddam Hussein’s forces had burrowed into deep concrete bunkers, impervious to existing US bombs like the BLU-109. Ground troops couldn’t reach them. Something had to give.
That’s when engineers from Lockheed Martin and the US Air Force turned artillery barrels into bomb casings. They used eight-inch M117 Howitzer barrels, reinforced them, added fins for flight stability, and fitted them with FMU-143 fuses for delayed detonation after impact.
Testing was frantic. On 24 February 1991, an F-111 dropped a GBU-28 in Nevada. It hit supersonic speeds and buried itself over 100 feet underground. Three days later, two GBU-28s were airlifted to Saudi Arabia and fitted on F-111 jets codenamed 'Cardinal 7-1' and 'Cardinal 7-2'.
"We got confirmation with smoke rising from the vents," a pilot radioed after the second bomb struck the bunker at Al Taji airbase.
Also Read: Israel conducts military strikes across Iran minutes after Trump declares ceasefire
GBU-28s: One Bomb, One Message
Only two GBU-28s were used during the Gulf War. One missed. The other hit. A day later, Iraqi troops surrendered. Many believed the bomb signalled that no shelter was deep enough. That same fear has now returned in Iran.
Since then, the GBU-28 has seen action in Yugoslavia, Afghanistan, and Iraq again in 2003. Israel acquired 100 of them in 2005, with deliveries completed by 2009. A 2009 US diplomatic cable suggested Israel saw them as essential for reaching Iran’s suspected nuclear sites.
Also Read: Missiles are back? Israel says Iran launched more missiles hours after start of ceasefire
Meet the GBU-57: The bigger bomb
The GBU-57 is the largest conventional bomb in the US military. It weighs 30,000 pounds and can penetrate 200 feet of soil or 60 feet of reinforced concrete. It’s guided by GPS and Inertial Navigation Systems and fitted with a Large Penetrator Smart Fuze to determine the right moment to explode.
Only the B-2 Spirit can carry it. Each bomber hauls two bombs, and seven of the US's 19 operational B-2s participated in the Iran mission.
Unlike the GBU-28, the GBU-57 uses grid fins for mid-air corrections. The weapon evolved from the GBU-37 and GBU-28 lineage and incorporates the BLU-127 bomb body. By 2015, only about 20 had been built.
Also Read: Israeli defence minister orders attacks on Iran after ceasefire 'violation'
Why now? why Iran?
The Trump administration believes Iran was just weeks away from building a nuclear weapon. US intelligence assessments reportedly disagreed. But Israel does not possess weapons powerful enough to breach facilities like Fordow or Natanz.
Some estimates say Fordow lies beneath 80 metres of soil and reinforced concrete. Only the GBU-57 could get through.
According to Reuters, the strikes may have destroyed significant portions of Iran’s nuclear infrastructure. But Iranian missile attacks on Israel have continued, and Tehran has not directly responded to the US.
Also Read: 'No agreement on ceasefire yet', says Iranian Foreign Minister Abbas Araghchi as Trump makes big claim
A dangerous precedent
Some analysts now worry the attack may drive Iran to double down on its nuclear ambitions. History offers sobering lessons. Ukraine surrendered its nuclear weapons in the 1990s. It later faced Russian invasions. Libya gave up its programme; Gaddafi fell. Meanwhile, North Korea tested a bomb in 2006 and has avoided foreign intervention since.
Iran may now decide that the only way to survive such strikes in the future is to develop its own nuclear deterrent.
Back in 1991, a single bomb marked the end of a war. In 2024, multiple bombs may just be the beginning of another chapter.
Even as the smoke clears over Fordow, questions remain. What else is hidden underground? And will deeper shelters or newer bombs come next?
The ghost of GBU-28 now casts a long shadow — over Tehran, and the world beyond.
"Obliteration is an accurate term!" US President Donald Trump declared after the strike. He later added, "A regime change will Make Iran Great Again," but US officials insisted that ' Operation Midnight Hammer' was not designed to overthrow Tehran.
The US also launched 30 Tomahawk cruise missiles at sites in Natanz and Isfahan. Satellite images from Maxar Technologies showed long lines of vehicles outside Fordow two days before the attack, suggesting Tehran had moved much of its 60% highly enriched uranium in advance. A senior Iranian source confirmed to Reuters that this stockpile was relocated to an undisclosed location.
Read more on the Israel-Iran ceasefire here
The return of the Bunker Buster
This wasn’t the first time America used bunker-busting bombs to alter the course of a conflict. During Operation Desert Storm in 1991, the US rushed to develop a weapon that could punch through 50 feet of reinforced concrete. The GBU-28 was built in just three weeks.
Saddam Hussein’s forces had burrowed into deep concrete bunkers, impervious to existing US bombs like the BLU-109. Ground troops couldn’t reach them. Something had to give.
That’s when engineers from Lockheed Martin and the US Air Force turned artillery barrels into bomb casings. They used eight-inch M117 Howitzer barrels, reinforced them, added fins for flight stability, and fitted them with FMU-143 fuses for delayed detonation after impact.
Testing was frantic. On 24 February 1991, an F-111 dropped a GBU-28 in Nevada. It hit supersonic speeds and buried itself over 100 feet underground. Three days later, two GBU-28s were airlifted to Saudi Arabia and fitted on F-111 jets codenamed 'Cardinal 7-1' and 'Cardinal 7-2'.
"We got confirmation with smoke rising from the vents," a pilot radioed after the second bomb struck the bunker at Al Taji airbase.
Also Read: Israel conducts military strikes across Iran minutes after Trump declares ceasefire
GBU-28s: One Bomb, One Message
Only two GBU-28s were used during the Gulf War. One missed. The other hit. A day later, Iraqi troops surrendered. Many believed the bomb signalled that no shelter was deep enough. That same fear has now returned in Iran.
Since then, the GBU-28 has seen action in Yugoslavia, Afghanistan, and Iraq again in 2003. Israel acquired 100 of them in 2005, with deliveries completed by 2009. A 2009 US diplomatic cable suggested Israel saw them as essential for reaching Iran’s suspected nuclear sites.
Also Read: Missiles are back? Israel says Iran launched more missiles hours after start of ceasefire
Meet the GBU-57: The bigger bomb
The GBU-57 is the largest conventional bomb in the US military. It weighs 30,000 pounds and can penetrate 200 feet of soil or 60 feet of reinforced concrete. It’s guided by GPS and Inertial Navigation Systems and fitted with a Large Penetrator Smart Fuze to determine the right moment to explode.
Only the B-2 Spirit can carry it. Each bomber hauls two bombs, and seven of the US's 19 operational B-2s participated in the Iran mission.
Unlike the GBU-28, the GBU-57 uses grid fins for mid-air corrections. The weapon evolved from the GBU-37 and GBU-28 lineage and incorporates the BLU-127 bomb body. By 2015, only about 20 had been built.
Also Read: Israeli defence minister orders attacks on Iran after ceasefire 'violation'
Why now? why Iran?
The Trump administration believes Iran was just weeks away from building a nuclear weapon. US intelligence assessments reportedly disagreed. But Israel does not possess weapons powerful enough to breach facilities like Fordow or Natanz.
Some estimates say Fordow lies beneath 80 metres of soil and reinforced concrete. Only the GBU-57 could get through.
According to Reuters, the strikes may have destroyed significant portions of Iran’s nuclear infrastructure. But Iranian missile attacks on Israel have continued, and Tehran has not directly responded to the US.
Also Read: 'No agreement on ceasefire yet', says Iranian Foreign Minister Abbas Araghchi as Trump makes big claim
A dangerous precedent
Some analysts now worry the attack may drive Iran to double down on its nuclear ambitions. History offers sobering lessons. Ukraine surrendered its nuclear weapons in the 1990s. It later faced Russian invasions. Libya gave up its programme; Gaddafi fell. Meanwhile, North Korea tested a bomb in 2006 and has avoided foreign intervention since.
Iran may now decide that the only way to survive such strikes in the future is to develop its own nuclear deterrent.
Back in 1991, a single bomb marked the end of a war. In 2024, multiple bombs may just be the beginning of another chapter.
Even as the smoke clears over Fordow, questions remain. What else is hidden underground? And will deeper shelters or newer bombs come next?
The ghost of GBU-28 now casts a long shadow — over Tehran, and the world beyond.
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