US attacks hurt but Iran’s nuclear ambition will endure

With stealth bombers and bunker busters, the US just punched a hole through the heart of Iran’s fortified nuclear program.

Multiple news outlets reported that US forces struck Iran’s three primary nuclear sites, Fordow, Natanz, and Isfahan, late Saturday (June 21) in a significant escalation of Middle East tensions. The operation follows Israel’s June 13 air offensive, which targeted suspected Iranian weapons development sites and other military targets.

In a televised address, US President Donald Trump declared the “spectacular” operation had “completely and totally obliterated” Iran’s enrichment facilities while warning of more precision strikes if Tehran refuses peace.

The US strikes involved B-2 bombers, six so-called bunker-buster bombs on Fordow and 30 Tomahawk missiles on Natanz and Isfahan. Iranian media said the sites were evacuated earlier. The IAEA said no radioactive contamination was detected from the attacked facilities.

Trump emphasized the US does not seek regime change and reached out diplomatically after the attack. Israeli Prime Minister Benjamin Netanyahu praised the strikes, calling them historic.

Iran maintains its program is peaceful and vowed to continue nuclear advancement. UN Secretary-General Antonio Guterres condemned the attack as a “dangerous escalation,” warning of global fallout.

The coordinated use of stealth bombers and deep-penetration munitions against Fordow, Natanz and Isfahan demonstrated a calibrated show of force aimed at degrading Iran’s breakout capability without crossing the threshold of full-scale war or regime decapitation.

Describing the defenses and importance of the Iranian nuclear sites just hit, CNN reports that Natanz, Iran’s largest enrichment complex, houses 50,000 centrifuges in hardened underground layers, where targeting subterranean power is key to disruption.

CNN adds that Fordow lies 80–90 meters beneath mountainous terrain, is impervious to most munitions and can rapidly produce weapons-grade uranium. It adds that Isfahan, central to Iran’s nuclear research and development, hosts three research reactors and multiple conversion and fuel production lines operated by 3,000 scientists.

CNN observes that these deeply embedded, high-output sites are both extremely resilient and strategically essential, making them high-risk yet high-priority in any strike calculus.

While Israel has previously attacked those facilities, it does not have any ordnance that could destroy deeply embedded facilities such as Fordow. A ground raid similar to the January 2025 operation against Iranian underground missile facilities in Syria is its only plausible option.

However, those nuclear sites are arguably much more distant, complex, heavily defended and fortified compared to the missile bases Israel raided in Syria, making an air attack with US-delivered ordnance was the better option to take them out.

According to Defense Today, the GBU-57 can penetrate over 200 feet of reinforced concrete using a high-density Eglin steel (ES-1) casing. According to the report, the GBU-57 carries 2,400 kilograms of AFX-757 and PBXN-114 explosives, ten times the power of its predecessor, the BLU-109.

Defense Today states the 20.5-foot GBU-57 is deployable only by B-2 bombers, two per plane, and is the US Air Force’s top option against fortified Weapons of Mass Destruction (WMD) targets.

Regarding the Tomahawk cruise missile, Naval Technology notes that the munition is designed for precision land-attack missions from naval platforms. The report states that the 1,300-kilogram, 5.56-meter subsonic cruise missile flies at 880 kilometers per hour and has a range of 1,600 kilometers.

Naval Technology says that, although in service since the 1980s, the Tomahawk’s Block V upgrade adds advanced navigation, satellite communications and in-flight retargeting capabilities. It adds that the missile could be armed with W80 nuclear warheads or a unitary 450-kilogram high-explosive warhead, with variants supporting submunitions and maritime strikes.

The War Zone (TWZ) notes that while specifics of the operation remain classified, the B-2s may have launched from Diego Garcia or forward locations under extreme secrecy, supported by extensive electronic warfare to disrupt Iranian command and control.

TWZ reports that the mission aimed to degrade critical enrichment infrastructure while minimizing exposure, marking the US’s kinetic entry into the Israel-Iran conflict.

While it may be too early to say whether the US strikes destroyed Iran’s nuclear sites, as Trump has claimed, Newsweek reports the targeted facilities were evacuated beforehand, suggesting significant quantities of highly enriched uranium (HEU) may have been removed.

Further, it remains unclear how Iran will respond to the massive blow to its nuclear program. According to Israeli National Security Advisor Tzachi Hanegbi, military strikes alone won’t destroy Iran’s nuclear program; Israel’s goal, as Brookings notes, is complete dismantlement, but that may be wishful thinking.

Underscoring this point, Carlo Caro writes in Cipher Brief that Iran’s nuclear infrastructure includes redundant nodes across military, academic and industrial sectors, possibly enabling rapid reconstitution after a strike.

Caro notes that Iran’s domestic centrifuge manufacturing eliminates reliance on foreign supply chains, while its passive defense doctrine mirrors North Korean survivability strategies.

He states that crucial assets, such as design archives, simulation models and trained personnel, are mobile, concealed and legally ambiguous under the terms of the Non-Proliferation Treaty (NPT). Thus, he suggests precision air campaigns will merely delay progress and cannot dismantle Iran’s institutionalized nuclear latency or strategic breakout potential.

Given those caveats, Brookings notes that overthrowing the Iranian theocratic regime may be the only way to eliminate Iran’s nuclear program. However, it warns that regime change is difficult and that a successor regime, most likely led by the Iranian Revolutionary Guards Corps (IRGC), is unlikely to be less interested in nuclear weapons than its predecessor.

Highlighting the difficulty of engineering regime change in Iran, Narges Bajoghli writes in Time that the Islamic Republic’s deeply entrenched, multilayered defense architecture and institutional resilience make regime change unfeasible.

Bajoghli points out that, unlike Iraq or Libya, Iran fields a dual military, the regular Artesh and the elite IRGC, backed by the pervasive Basij network, enabling asymmetric warfare and internal control. She emphasizes that decades of siege doctrine, hardened by war and sanctions, have fostered a system built for survival, not collapse.

Bajoghli also writes that Iran’s leadership is decentralized under a competitive authoritarian framework, enabling continuity even under duress. She stresses that foreign-imposed regime change would likely galvanize nationalist resistance, replicating Iraq’s catastrophic aftermath after the fall of Saddam Hussein.

Rather than destabilize the Iranian regime, Bajoghli says airstrikes risk reinforcing Iran’s nuclear deterrence doctrine and undermining prospects for diplomacy.

Further, an emboldened and determined Iran doubling down on its nuclear program could lead to a Middle Eastern nuclear arms race. Saudi Crown Prince Mohammed bin Salman, for one, has warned his country would acquire nuclear weapons if Iran crossed that threshold.