U.S.’s heavy duty attack on Iran’s nuke sites

The story so far:

On June 21, U.S. President Donald Trump announced that the U.S. military carried out precision strikes on three key Iranian nuclear facilities, mainly Fordow, Natanz and Isfahan. He further stated that the strikes were a “spectacular” military success and that Iran’s key nuclear enrichment facilities have been “completely and totally obliterated”. The key part of these strikes were conducted by the B-2 Spirit stealth bombers which dropped GBU-57 bunker busters to penetrate the Fordow enrichment facility located deep inside a mountain, that was beyond the capability of Israel. Later on Sunday, U.S. Secretary of Defence Pete Hegseth and Gen. Dan Caine, Chairman of the Joint Chiefs of Staff detailed the strikes carried out by the U.S. Central Command (Centcom) under ‘Operation Midnight Hammer’.

How were the strikes carried out?

After proceeding quietly and with minimal communication for 18 hours from the U.S. to the target area, the first of the seven B-2 Spirit stealth bombers dropped two 30,000 lb GBU-57 Massive Ordnance Penetrator (MOP) ‘bunker buster’ bombs at the Fordow site at approximately 6:40 p.m. EDT, Gen. Caine told media houses. The initial mission package also included several decoy aircraft that flew west over the Pacific Ocean as “a deception effort known only to an extremely small number of planners and key leaders here in Washington,” he stated.

“The U.S. employed several deception tactics — including decoys — as the fourth and fifth generation aircraft pushed out in front of the strike package at high altitude and high speed, sweeping in front of the package for enemy fighters and surface-to-air missile threats”, according to Gen. Caine. “Following the initial strike on Fordow, the remaining B-2s went on to deploy their ordnance, eventually totalling 14 MOPs hitting the targeted areas,” he said noting that this was the first operational use of the GBU-57 MOP.

In addition to the MOPs, a U.S. submarine launched more than two dozen Tomahawk land attack cruise missiles at key infrastructure targets at the Isfahan site, bringing the overall total of precision-guided weapons employed during the operation to approximately 75. “Initial battle damage assessments indicate that all three sites sustained extremely severe damage and destruction,” Gen. Caine stated, although later in the day several U.S. officials expressed doubts on the extent of damage to the Fordow facility.

What is a B-2 stealth bomber?

The U.S. Air Force (USAF) operates the country’s bomber fleet which consists of 114 B-1 Lancers, 21 B-2 Spirit and 137 legacy B-52 aircraft. Of these, B-2 is the only fully stealth aircraft while the B-1 has some stealth features. Each B-2 costs over $2 billion, the most expensive aircraft ever, and so only 21 aircraft were built. One B-2 crashed in 2008 while another was damaged in 2022, and with the repair work deemed prohibitive, it is set to be retired soon. This leaves only 19 B-2 aircraft in active inventory.

The B-2 has always inspired awe with its bat-like shape, and has been extensively showcased by Hollywood. It is a dual-capable multi-role heavy bomber, powered by four engines. According to the USAF, the B-2’s low observability is derived from a combination of reduced infrared, acoustic, electromagnetic, visual and radar signatures. “These signatures make it difficult for sophisticated defensive systems to detect, track and engage the B-2,” the USAF states. The B-2 made its first flight in 1989 and began operations in 1997. With a crew of two, it can carry a payload of 40,000 lb, has an un-refuelled range of 6,000 miles and a service ceiling of 50,000 feet. It is 69 feet long, 17 feet high and has a wingspan of 172 feet, half the length of a football field.

For Sunday’s mission, the B-2s flew 37-hours non-stop, from their home base to the target location and back, re-fuelling several times mid-air, making it the second longest mission ever. The B-2s hold the record for the longest air combat mission in history. As per its manufacturer Northrop Grumman, in 2001, six B-2s were the first to enter Afghan airspace for a record setting 44-hour mission. According to an article in the New York Post, the B-2 pilots “have their cockpits outfitted with mini refrigerators and a microwave oven to keep their crew fed and alert” and also have a toilet and enough space for one person to lay down and rest.

A March 2025 report of the U.S. Congressional Research Service (CRS) states that the USAF continues to modernise the B-2. Northrop Grumman was awarded a contract in 2024 of up to $7 billion to maintain and improve B-2 stealth and communications capabilities, engines, and displays through 2029.

The B-2s are extremely maintenance intensive. According to a detailed account in The Atlantic on the B-2s employed in Libya in 2018, 100 hours of maintenance were required for every hour of flight. This is mainly because the advantage of stealth is B-2’s edge, and it is achieved by design and radar-absorbing materials. To maintain them, the aircraft needs temperature controlled hangers to protect against changes in temperature, humidity, and dust.

Why was there a need for ‘bunker-busters’?

The nuclear fuel enrichment site at Fordow is located 60 miles south of Iran’s capital Tehran in the mountainous region close to the city of Qom. The facilities are buried deep underground, estimated to be 80-90m deep, to withstand Israeli airstrikes. Iran acknowledged its existence only in 2009. That’s why there was a need for the GBU-57 MOP and the B-2 Spirit that can carry it. It also meant that the U.S. had to officially enter the Israel-Iran conflict which began on June 13, when Israel started bombing Iranian nuclear and military facilities.

The GBU-57 MOP, according to the USAF is a weapon system designed “to accomplish a difficult, complicated mission of reaching and destroying our adversaries’ weapons of mass destruction located in well protected facilities.” It is more powerful than its predecessor, the BLU-109 and the GBU-28. According to USAF, a total of 20 MOPs were contracted. The B-2 Spirit is the only aircraft in the USAF capable of employing the 20.5 ft, 30,000 lb MOP which is guided by GPS to reach and destroy targets. Given the weight, each B-2 can hold two MOP bombs.

According to a 2012 CRS report, the GB-57 has a penetration capability of up to 200 feet underground before exploding. “By some reports, it was expected to penetrate as much as 200 feet through 5,000 psi reinforced concrete, and 25 feet into 10,000 psi reinforced concrete,” it states. The New York Times quoted a senior U.S. official who stated that the strike on the Fordow site did not destroy the heavily fortified facility but has severely damaged it, taking it “off the table.” The person noted that even 12 bunker-busting bombs could not destroy the site.

What next?

This mission was not, and has not been, about regime change, Mr. Hegseth said. “The president authorised a precision operation to neutralise the threats to our national interests posed by the Iranian nuclear program and [in support of] the collective self-defense of our troops and our ally, Israel.” However, it is unclear whether the objectives of fully neutralising the nuclear enrichment facilities of Iran has been accomplished. Moreover, the whereabouts of the enriched uranium are unknown, as per U.S. officials.

A next generation bomber, the B-21 Raider, a dual-capable penetrating-strike stealth bomber, is currently under development. The B-21 is similar to the B-2, but slightly smaller, with a distinctive beak domed centre. According to a USAF fact sheet, the B-21 has been designed with an open systems architecture to allow for faster new software integration. With a plan to make them enter service in the next few years, the USAF is looking at acquiring a minimum of 100 aircraft at an average unit procurement cost of $550 million.

Published – June 25, 2025 08:30 am IST