Located deep below a mountain, Iran’s Fordow nuclear site was always going to be a tough target for Israel.
Israeli weapons would struggle to reach it—but the U.S.’s arsenal can. American B-2 Spirit bombers, equipped with one of the world’s heaviest non-nuclear bombs, are thought to be the only aircraft-and-bomb pairing able to destroy a target like the nuclear plant at Fordow.
The 30,000 pound GBU-57/B bunker buster, also known as the Massive Ordinance Penetrator (MOP), would very likely be the weapon of choice if President Donald Trump gave the green light to U.S. involvement in Israel’s strikes on Iran’s nuclear program.
So far, the White House has signaled a reluctance to wade into the fighting in the Middle East, now entering its fifth day.
Cherie A. Thurlby/U.S. Air Force/Getty Images
The U.S. administration appears to be “keeping its options open” as of early morning on the east coast, Michael Oren, former Israeli ambassador to the U.S., told Newsweek.
But Israeli sources say the mood in the country has changed overnight. It seems “more and more tangible” that the U.S. could become involved in targeting Iran’s nuclear sites, said Shuki Friedman, director-general at the Jewish People Policy Institute, an Israeli think tank.
Israel early on Friday local time launched “preemptive” strikes on Iran’s nuclear program, its ballistic missile sites and other military facilities. Israel has continued to strike across the country as Iran targeted Israel with drones and missiles, some of which evaded Israel’s extensive air defenses.
“It’s possible we could get involved,” Trump told ABC on Sunday. “But we are not at this moment involved.”
What Has Trump Done So Far?
To embroil the U.S. in the conflict would be a significant step. Trump has warned Iran—which has cast the U.S. as already involved—that Tehran would face “the full strength and might” of the U.S. military on “levels you’ve never seen before” if Iran attacked the U.S. in any way.
Trump left the G7 summit in Canada on Monday, but said his early departure from the major meeting was not related to a deal to stop the fighting between Iran and Israel.
French President Emmanuel Macron had told reporters there was an “offer” on the table for a ceasefire. Trump, referencing the comments on his Truth Social platform, called the French president “publicity seeking,” adding: “He has no idea why I am now on my way to Washington, but it certainly has nothing to do with a Cease Fire.”
“Much bigger than that,” Trump added. In a later post, the president called for residents of Iran’s capital to “immediately evacuate.” Fordow is roughly 100 miles from Tehran.
Trump separately told reporters on Monday he wanted a “real end” to discussions over nuclear capabilities with Tehran, with the country “giving up entirely” on nuclear weapons, according to a CBS reporter.
“I didn’t say I was looking for a ceasefire,” Trump told the journalist.
Sean Parnell, the Pentagon’s chief spokesperson, said U.S. forces had “not changed” their “defensive posture.”
But everything is “in place” for a U.S. entry into the Israeli strike campaign, Friedman told Newsweek.
The U.S. is moving its USS Nimitz aircraft carrier toward the Middle East, and Israel’s air force has worked hard to wipe out Iranian air defenses that could threaten both its advanced aircraft and, theoretically, U.S. bombers.
Israel targeted part of a Russian-made S-300 air defense system around the central Iranian city of Isfahan in April. Wider attacks in October then destroyed the remaining S-300s at Iran’s disposal, Israel said.
This left Iran “vulnerable” to additional strikes and to Israeli F-35s, said Daniel Shapiro, a former U.S. ambassador to Israel now at the Atlantic Council. It will be unable to replace these losses in the short-term, he told Newsweek on Monday.
Israel also targeted air defenses in Syria at the end of 2024 after the country’s regime, led by former leader Bashar al-Assad, collapsed.
What Are the B-2 and the MOP?
Israel has an advanced air force, kitted out with fifth-generation F-35i stealth fighters that targeted many of Iran’s air defenses, plus the F-15 and F-16 jets that then swooped in with bombs and missiles.
But it does not have any bombers capable of ferrying the likes of the GBU-57/B. The B-2 is the only aircraft cleared to carry the bunker buster in combat, although the B-52 has tested the MOP.
The distinctively designed and stealthy B-2 Spirit has a crew of two and is able to launch conventional or nuclear weapons. The U.S. Air Force has 19 operational B-2A aircraft, according to the U.K.-based International Institute for Strategic Studies (IISS), which publishes annual counts of the world’s armed forces.
The B-2 was designed to skirt the Soviet Union’s air defenses and deliver nuclear strikes, said William Alberque, a visiting fellow at the Henry L. Stimson Center and a former director of NATO’s Arms Control, Disarmament and WMD Non-Proliferation Center.
The stealth bombers, able to cover enormous distances without stopping to refuel, were adapted to carry large conventional bombs, he told Newsweek.
The MOP is a descent of the weapon nicknamed the “mother of all bombs” in the Iraq war era, Alberque said, but was upgraded to be smaller and able to penetrate further into hardened targets.
Israel, without the B-2 and the MOP, could still strike Fordow, analysts say. But it would take a huge amount of Israel’s much smaller bombs, across many, many strikes, to hit deep into Fordow, and could expose aircraft targeting the nuclear site to Iran’s remaining air defenses and mobile equipment.
Even the American B-2 would need to strike Fordow more than once to collapse more than the entrance and damage the centrifuge hall, Alberque said.
But without knocking out Fordow, Alberque said, Israel cannot credibly say it has destroyed Iran’s ability to build a nuclear bomb. It is also not clear, at least in the public domain, how much of Iran’s highly enriched uranium remains and how many centrifuges the regime actually has.
Damage to Iran’s Nuclear Sites
Experts say there is no visible damage at Fordow since Israel started its strike campaign last week.
The United Nations’ nuclear watchdog assessed on Monday that Israel had “severely damaged if not destroyed” centrifuges at the underground facility in Natanz, one of the three major nuclear sites in Iran. Centrifuges enrich uranium.
The below-ground centrifuges were not hit directly, but Israeli strikes caused power cuts and “completely destroyed” the above-ground Natanz site, Rafael Grossi, the chief of the International Atomic Energy Agency (IAEA) told the BBC.
In separate remarks, the IAEA chief said the watchdog had not seen any fresh damage to Natanz since Friday.
Satellite imagery published by Maxar on Monday showed vehicle tracks over the same areas where craters were visible the previous day. Four buildings were damaged at Isfahan, another major nuclear site in central Iran, Grossi said.
How Close Was Iran To a Nuclear Weapon?
The U.S. and Israel have repeatedly said it would be unacceptable for Iran to get hold of a nuclear weapon. “Simply stated, IRAN CAN NOT HAVE A NUCLEAR WEAPON,” Trump said on Monday.
The IAEA has warned for months Iran was producing uranium enriched up to 60 percent.
The higher the percentage, the more efficient a nuclear weapon would be. Uranium enriched to 60 percent could theoretically be used for a nuclear weapon, albeit an inefficient one by most standards. Weapons-grade enriched uranium is considered to be 90 percent.
The IAEA said last week Iran was not cooperating with its nuclear obligations for the first time in 20 years. Tehran said it would get a new enrichment site in a “secure location” up and running.
Iran says its nuclear program is peaceful. But senior officials have publicly debated developing a nuclear weapon.
A 2015 agreement, known as the Joint Comprehensive Plan of Action (JCPOA), or simply as the Iran nuclear deal, relieved sanctions leveled against Iran in exchange for new limits on Tehran’s nuclear program. Also, the powers involved at the time tried to limit weapons sales to and from Iran, as well as the country’s ballistic missile development.
However, Iran has openly said it has abandoned parts of the JCPOA since Trump pulled the U.S. out of the deal during his first time in office.
Trump, since returning to the White House in January, has threatened to unleash “bombing the likes of which they have never seen” on Iran if it doesn’t ink a deal to limit its nuclear program.
Iran says it will not enter discussions on a deal while under Israeli attack.
