In a striking revelation that underscores both the complexity and limits of modern military power, General Dan Caine, the U.S. military’s top general for strategic operations in the Middle East, disclosed in a closed-door Senate session why the U.S. did not employ the formidable GBU-57 Massive Ordnance Penetrator (MOP) during the recent joint American-Israeli air campaign targeting Iran’s nuclear infrastructure.
According to a CNN report corroborated by three individuals present during the briefing and a fourth briefed on its content, General Caine explained that the underground nuclear facility in Isfahan is buried so deep beneath reinforced layers of rock and concrete that even the 30,000-pound bunker buster would have had limited or no effect. This marks the first official U.S. military acknowledgment of the operational limits of the MOP in the context of Iran’s heavily fortified nuclear sites.
This admission, though not publicized by the Pentagon, comes after an extraordinary display of U.S. airpower in what has now been dubbed the largest coordinated strike against Iranian nuclear assets since the inception of the Islamic Republic.
The scale of the operation was staggering. Over 125 U.S. military aircraft participated, including seven B-2 Spirit stealth bombers — the most deployed in a single strike in American history — along with fighter escorts, aerial tankers, surveillance drones, and command-and-control aircraft. Complementing this formidable aerial armada was a guided missile submarine positioned in the Persian Gulf, which launched more than two dozen Tomahawk cruise missiles aimed at Iran’s Isfahan site and other strategic infrastructure.
Fordow and Natanz, Iran’s better-known uranium enrichment sites, bore the brunt of the aerial bombing. The B-2s, flying round trips from Whiteman Air Force Base in Missouri, dropped more than a dozen GBU-57 MOPs on these underground facilities. However, for Isfahan — which U.S. intelligence believes houses nearly 60% of Iran’s enriched uranium stockpile — commanders opted for submarine-launched cruise missiles rather than bunker busters.
“The site was simply too deep. Using the MOP would not have accomplished the mission objective,” said one official familiar with General Caine’s remarks.
Isfahan’s enrichment infrastructure had long been suspected to be Iran’s most secure and clandestine uranium storage site, far surpassing Fordow and Natanz in terms of physical protection. According to defense analysts, the site includes a subterranean labyrinth extending hundreds of meters underground, protected by multiple blast doors, reinforced layers of limestone, and electromagnetic shielding to complicate targeting.
That Isfahan was not targeted with bunker-busters raises questions about the true extent of damage inflicted. Yet, the Pentagon maintains that the Tomahawk strike caused extensive surface-level and sub-surface disruption.
“These missiles fly low, fast, and follow pre-programmed evasive routes,” General Caine explained at a subsequent press briefing. “This was the only feasible way to reach the site in its entirety.”
Former President Donald Trump, speaking at a high-profile press event in Palm Beach shortly after the operation, called the strike “a spectacular military success” and claimed it had set Iran’s nuclear program “back by decades.”
Defense Secretary Pete Hegseth echoed the sentiment, criticizing media outlets for reporting on leaked intelligence assessments that suggested a far more limited impact. “President Trump created the conditions to end the war, decimating — choose your word — obliterating, destroying Iran’s nuclear capabilities,” Hegseth told Pentagon journalists.
Yet, conflicting narratives soon emerged, sowing confusion about the true effectiveness of the operation.
Within days of the strike, U.S. intelligence officials leaked a preliminary assessment suggesting that the operation had only delayed Iran’s nuclear program by several months. This sharply contrasted with official statements.
The leak triggered a political firestorm. Defense Secretary Hegseth denounced it as “an effort to sabotage the narrative of success,” while CIA Director John Ratcliffe attempted to reassure skeptics, citing sources that claimed “several key Iranian nuclear facilities were destroyed and would need to be rebuilt over the course of years.”
Still, some observers questioned whether Iran had managed to evacuate large portions of its enriched uranium stockpile prior to the strike. According to European intelligence agencies, there is “credible evidence” that more than 400 kilograms of uranium enriched to 60 percent — just a technical step away from weapons-grade — had been quietly moved to alternate locations in anticipation of an imminent attack.
This amount, if further enriched, could theoretically yield material for up to nine nuclear warheads.
Israeli Prime Minister Benjamin Netanyahu declared the campaign a “historic victory,” stating that it had “delayed Iran’s nuclear capability by several years.” Israeli military officials described their role in the operation as “limited but essential,” contributing intelligence, electronic warfare capabilities, and precision targeting data.
However, Israeli assessments were more cautious in tone. A senior IDF officer speaking anonymously acknowledged that the full extent of the operation’s impact would take months to assess.
“We delivered a significant hit, but Iran’s capacity to rebuild should not be underestimated,” the official said.
In Tehran, Iran’s leadership sent mixed messages. Supreme Leader Ayatollah Ali Khamenei dismissed the U.S. and Israeli claims, stating that the attack had done “nothing significant” to Iran’s nuclear infrastructure. “The American president exaggerated events in unusual ways,” he said in a televised speech.
But Iran’s foreign minister, Abbas Araghchi, took a different line. Speaking at an emergency session of the Iranian parliament, he called the damage “serious,” adding that a full assessment was ongoing.
Meanwhile, a senior adviser to Khamenei, Ali Shamkhani, insisted that Iran’s nuclear stockpile remained intact. “Even if nuclear sites are destroyed, the game isn’t over,” he said. “Enriched materials, indigenous knowledge, and political will remain.”
Perhaps the most alarming development for the international community was the Iranian parliament’s passage of a bill suspending cooperation with the International Atomic Energy Agency (IAEA). The legislation was quickly approved by Iran’s Guardian Council and now awaits formal ratification by the president.
The IAEA’s Director-General Rafael Grossi described the situation as “deeply concerning.”
“In recent days, we have been unable to verify the state of critical facilities,” Grossi told French broadcaster RFI. “I believe ‘annihilated’ is too strong. But it (Iran’s nuclear program) has suffered enormous damage.”
Grossi confirmed that thousands of centrifuges — highly sensitive machines used to enrich uranium — had been destroyed or rendered inoperable by the blasts. He also noted that Iran’s capacity to continue enrichment at pre-strike levels was now “severely constrained.”
The unprecedented air campaign signals a major inflection point in the years-long standoff over Iran’s nuclear ambitions. It underscores both the potency and limits of kinetic military options, especially when facing deeply buried, hardened facilities.
Experts agree that while the strikes inflicted major damage, the operation may not have achieved all its strategic objectives. “The strikes were successful tactically, but if Iran has indeed dispersed its enriched uranium stockpiles, the long-term impact is questionable,” said Dr. Laura Sloane, a senior fellow at the Center for Strategic and International Studies.
Others point out that the operation might fuel further Iranian defiance. “We’re entering a more dangerous phase,” said retired General Mark Hertling. “Iran may now pursue its program more covertly, with less regard for IAEA protocols.”
In the final analysis, the operation that combined stealth bombers, submarine-launched missiles, and real-time intelligence feeds from dozens of surveillance drones may well stand as one of the most complex and ambitious military campaigns in modern history. But its strategic outcomes remain uncertain.
If Iran’s nuclear capabilities have indeed been “set back by decades,” as claimed by President Trump, it will likely reshape the regional security landscape in dramatic ways. However, if the strikes merely caused disruption and Iran still possesses large amounts of enriched uranium, then the campaign — however spectacular in execution — may only delay the inevitable.
