Late on Saturday night, local time, the United States carried out strikes against Iranian nuclear enrichment sites at Fordow, Natanz and Isfahan.
The US says it fired 30 submarine-launched missiles at the sites in Natanz and Isfahan, as well as dropping more than a dozen “bunker buster” bombs at Fordow and Natanz.
The kind of bomb in question is the extremely destructive GBU-57 Massive Ordance Penetrator, or MOP, which weighs around 13.5 tonnes.The attacks raise a lot of questions. What are these enormous bombs? Why did the US feel it had to get involved in the conflict? And, going forward, what does it mean for Iran’s nuclear ambitions?
What are ‘bunker busters’, and why are they used?
Bunker busters are weapons designed to destroy heavily protected facilities such as bunkers deep underground, beyond the reach of normal bombs.
Bunker busters are designed to bury themselves into the ground before detonating. This allows more of the explosive force to penetrate into the ground, rather than travelling through the air or across the surface.
Iran’s nuclear enrichment sites at Fordow, Natanz and Isfahan are built deep underground. Estimates suggest that Fordow for example could be 80m beneath the surface, and capped with layers of reinforced concrete and soil.
What is the MOP?
The bunker buster used in this particular operation is the largest in the US arsenal. Leaving aside nuclear weapons, the MOP is the largest known bunker buster in the world.
Weighing some 13.5 tonnes, the MOP is believed to be able to penetrate up to 60 metres below ground in the right conditions. It is not known how many the US possesses, but the numbers are thought to be small (perhaps 20 or so in total).
We also don’t know exactly how many were used in Iran, though some reports say it was 14. However, it is likely to be a significant portion of the US MOP arsenal.
Why does only the US possess this capability?
The US is not the only state with bunker-busting weaponry. However, the size of MOP means it requires very specialised bombers to carry and drop it.
Only the B2 stealth bomber is currently able to deploy the MOP. Each B2 can carry at most two MOPs at a time. Around seven of America’s 19 operational B2s were used in the Iran operation.
There has been some consideration whether large transport aircraft such as the C-130 Hercules could be modified to carry and drop the MOP from its rear cargo doors. While this would allow other countries (including Israel) to deploy the MOP, it is for now purely hypothetical.
Why has the US (apparently) used them in Iran
The Trump administration claims Iran may be only a few weeks from possessing a nuclear weapon, and that it needed to act now to destroy Iranian nuclear enrichment sites. This claim is notably at odds with published assessments from the US intelligence community.
However, Israel lacks bunker-busting weaponry sufficient to damage the deeply buried and fortified enrichment sites at Fordow, Natanz and Isfahan.
An F-15E Strike Eagle releases a GBU-28 ‘bunker buster’ laser-guided bomb, a smaller equivalewnt of the 13,600 kg GBU-57 ‘Massive Ordnance Penetrator’ believed to have been used in Iran. Michael Ammons / US Air Force
Only the MOP could do the job (short of using nuclear weapons). Even then, multiple MOPs would have been required to ensure sufficient damage to the underground facilities.
The US has claimed that these sites have been utterly destroyed. We cannot conclusively say whether this is true.
Iran may also have other, undeclared nuclear sites elsewhere in the country.
Iran’s reaction
The US has reportedly reached out to Iran via diplomatic channels to emphasise that this attack was a one-off, not part of a larger project of regime change. It is hard to say what will happen in the next few weeks.
Iran may retaliate with large strikes against Israel or against US forces in the region. It could also interrupt shipping in the Strait of Hormuz, which would affect a large portion of global oil shipments, with profound economic implications.
Alternatively, Iran could capitulate and take steps to demonstrate it is ending its nuclear program. However, capitulation would not necessarily mean the end of Iran’s nuclear ambitions.
The value of nuclear weapons
Perhaps a greater concern is that the attack will reinforce Iran’s desire to go nuclear. Without nuclear weapons, Iran was unable to threaten the US enough to deter today’s attack.
Iran may take lessons from the fate of other states. Ukraine (in)famously surrendered its stockpile of former Soviet nuclear weapons in the early 1990s. Russia has since felt emboldened to annex Crimea in 2014 and launch an ongoing invasion in 2022. Other potential nuclear states, such as Iraq and Gadaffi’s regime in Libya, also suffered from military intervention.
By contrast, North Korea successfully tested its first nuclear weapon in 2006. Since then there has been no serious consideration of military intervention in North Korea.
Iran may yet have the ability to produce useful amounts of weapons-grade uranium. It may now aim to buy itself time to assemble a relatively small nuclear device, similar in scale to the bombs used in Hiroshima and Nagasaki.
Depending on what facilities and resources have survived the US strikes, the attack has likely reinforced that the only way the Iranian regime can guarantee its survival is to possess nuclear weapons.
After two years of violence and the deaths of 68,000 Palestinians and more than 1,200 Israelis, most of them civilians, it has been reported that Hamas and the Netanyahu government will sign a phase 1 ceasefire agreement.
This is the first part of a 20-point plan promoted by the US president, Donald Trump, and supported by the major Arab power brokers in the region.
What we know so far is that Israel will cease its military assault in Gaza. Hamas, meanwhile, has agreed to free the remaining 20 Israeli hostages still alive in Gaza.
The Conversation’s international affairs editor Jonathan Este spoke with Scott Lucas, a Middle East expert at University College Dublin, who addressed several key issues.
How is this different to previous ceasefire agreements?
Until we have details, this agreement is similar to the phase 1 60-day ceasefire at the start of 2025. There is a pause in the killing, particularly from the Israeli side, but lasting arrangements remain to be confirmed.
The key difference is that Hamas released only some hostages and bodies in the previous ceasefire. This time they are freeing all hostages and the bodies which can be collected, in return for a still unannounced number of Palestinian detainees released from Israeli prisons.
That gives up Hamas’s main leverage against not only Israeli attacks but also the Netanyahu government’s occupation and veto on aid to Gaza.
So key elements of a lasting deal – the extent of the Israeli military’s withdrawal, the restoration of aid, the establishment of governance and security in the Strip – will rest on guarantees and who provides them.
What are the possible sticking points for the rest of the deal?
The immediate “sticking points” are whether central provisions will be agreed in further discussions.
The Israelis will demand complete disarmament by Hamas and possibly the expulsion of some of its officials. Hamas is likely to respond with rejection of any forced removals and its retention of “defensive” weapons.
The make-up of the international “board” overseeing the strip is vague beyond Donald Trump declaring himself the chair and no provision for any Palestinian representation. Hamas will probably seek some Palestinian membership.
At this point, the International Stabilization Force for the Strip is a wish rather than a plan. Israeli agreement to a force replacing its military in Gaza is far from assured, especially as it is not clear who will contribute personnel. The Italian foreign minister, Antonio Tajani, has offered to send troops to contribute to the force.
The plan for a day-to-day government to administer the Strip is equally sketchy. While the presence of Palestinian technocrats is mentioned in Trump’s “plan”, we do not know who these will be. We know that Hamas is excluded. Israel is also likely to veto the Palestinian Authority in the short-term. And the release from imprisonment of potential Palestinian leaders – such as Marwan Barghouti, who has been held by Israel for more than 20 years – is not confirmed.
And before consideration of all of these, there is the question of the far-right in the Netanyahu cabinet. The finance minister, Bezalel Smotrich, and national security minister, Itamar Ben-Gvir, have yet to comment on the latest news, but have previously opposed any deal short of the “total” defeat of Hamas and a long-term Israeli occupation. Neither have threatened to block the agreement – so far – but they have expressed opposition.
How much of this is due to pressure from Arab states?
While many headlines are likely to give the credit to Trump and his envoys, son-in-law Jared Kushner and real estate developer Steve Witkoff, the role of Arab states has been vital.
A month after Israel shattered Qatar’s sovereignty with the airstrike trying to assassinate Hamas’s negotiators, the Gulf state and Egypt were the brokers of this Phase 1 agreement. Behind the scenes, other Arab states and Turkey were urging Hamas to accept the Trump “plan” in principle and to reach a deal to release the hostages.
Those states will be needed for the next phase, particularly if Trump threatens to return to his previous position of a blank cheque for Israeli military operations and cut-off of aid.
Is there a future for Palestinian civilians in Gaza?
I hope so. The immediate issue is survival. The Israeli attacks have been paused. The urgent issue is getting essential aid into the Strip. Then it is a matter of being able to return to what is left of homes. The Trump administration has dropped its talk of displacement, stemming the demand of Netanyahu’s far-right ministers for the removal of many Gazans.
However, after two years of scorched-earth tactics by Israel, little is left of many of those homes. The majority of the health sector has been destroyed, as have many schools and other public buildings. Rafah has been razed, and Gaza City’s high rises have been blown apart.
Recovery cannot just focus on the profits to be made – including for Trump, Kushner, and Gulf state business interests – from the “development” of Trump’s “Riviera of the Middle East”. It has to begin with day-to-day subsistence for the civilians who have paid the heaviest price in this mass killing.
Does Trump get his Nobel peace prize now?
I don’t care. Sometimes good things happen from a convergence of cynical and self-serving motives. Trump is desperate for the Nobel peace prize because Barack Obama received it in 2009. Kushner, whose investment fund is bankrolled by Saudi Arabia and Qatar, and Gulf state entrepreneurs see the possibility of large profits. US-Gulf relations need to be repaired after the shock of Israel’s airstrike inside Qatar.
If that means lives are saved, fine. But those lives need to be saved not just for today or tomorrow. They need to be respected and supported with a lasting agreement for security and welfare.
And that would mean a two-state solution for both Palestinians and Israelis – something which the Netanyahu government and the Trump administration will not countenance. For Netanyahu and his ministers are devoted to expanding Israel’s illegal settlements, with the accompanying threat of violence, in the West Bank.
Celebrate phase 1 on the behalf of the Israeli hostages, their families, and Gaza’s civilians. And be clear about what is needed for phase 2, phase 3 and beyond.
President Donald Trump set the tone for his second term by issuing 26 executive orders, four proclamations and 12 memorandums on his first day back in office. The barrage of unilateral presidential actions has not yet let up.
These have included Trump’s efforts to remove thousands of government workers and fire several prominent officials, such as members of the Corporation for Public Broadcasting and the chair of the Commission on Civil Rights. He has also attempted to shut down entire agencies, such as the Department of Education and the U.S. Agency for International Development.
As a political science scholar who studies presidential power, I believe Trump’s recent actions mark the culmination of the unitary executive theory, which is perhaps the most contentious and consequential constitutional theory of the past several decades.
A prescription for a potent presidency
In 2017, Trump complained that the scope of his power as president was limited: “You know, the saddest thing is that because I’m the president of the United States, I am not supposed to be involved with the Justice Department. I am not supposed to be involved with the FBI, I’m not supposed to be doing the kind of things that I would love to be doing. And I’m very frustrated by it.”
The unitary executive theory suggests that such limits wrongly curtail the powers of the chief executive.
Formed by conservative legal theorists in the 1980s to help President Ronald Reagan roll back liberal policies, the unitary executive theory promises to radically expand presidential power.
There is no widely agreed upon definition of the theory. And even its proponents disagree about what it says and what it might justify. But in its most basic version, the unitary executive theory claims that whatever the federal government does that is executive in nature – from implementing and enforcing laws to managing most of what the federal government does – the president alone should personally control it.
This means the president should have total control over the entire executive branch, with its dozens of major governmental institutions and millions of employees. Put simply, the theory says the president should be able to issue orders to subordinates and to fire them at will.
President Donald Trump signs executive orders in the Oval Office next to a poster displaying the Trump Gold Card on Sept. 19, 2025. AP Photo/Alex Brandon
The president could boss around the FBI or order the U.S. attorney general to investigate his political opponents, as Trump has done. The president could issue signing statements – a written pronouncement – that reinterpret or ignore parts of the laws, like George W. Bush did in 2006 to circumvent a ban on torture. The president could control independent agencies such as the Securities and Exchange Commission and the Consumer Product Safety Commission. The president might be able to force the Federal Reserve to change interest rates, as Trump has suggested. And the president might possess inherent power to wage war as he sees fit without a formal authorization from Congress, as officials argued during Bush’s presidency.
A constitutionally questionable doctrine
A theory is one thing. But if it gains the official endorsement of the Supreme Court, it can become governing orthodoxy. It appears to many observers and scholars that Trump’s actions have intentionally invited court cases by which he hopes the judiciary will embrace the theory and thus permit him to do even more. And the current Supreme Court appears ready to grant that wish.
Until recently, the judiciary tended to indirectly address the claims that now appear more formally as the unitary executive theory.
During the country’s first two centuries, courts touched on aspects of the theory in cases such as Kendall v. U.S. in 1838, which limited presidential control of the postmaster general, and Myers v. U.S. in 1926, which held that the president could remove a postmaster in Oregon.
In 1935, in Humphrey’s Executor v. U.S., the high court unanimously held that Congress could limit the president’s ability to fire a commissioner of the Federal Trade Commission. And in Morrison v. Olson the court in 1988 upheld the ability of Congress to limit the president’s ability to fire an independent counsel.
Some of those decisions aligned with some unitary executive claims, but others directly repudiated them.
These decisions clearly suggest that long-standing, anti-unitarian landmark decisions such as Humphrey’s are on increasingly thin ice. In fact, in Justice Clarence Thomas’ 2019 concurring opinion in Seila Law LLC v. CFPB, where the court ruled the Consumer Financial Protection Bureau’s leadership structure was unconstitutional, he articulated his desire to “repudiate” the “erroneous precedent” of Humphrey’s.
Several cases from the court’s emergency docket, or shadow docket, in recent months indicate that other justices share that desire. Such cases do not require full arguments but can indicate where the court is headed.
In Trump v. Wilcox, Trump v. Boyle and Trump v. Slaughter, all from 2025, the court upheld Trump’s firing of officials from the National Labor Relations Board, the Merit Systems Protection Board, the Consumer Product Safety Commission and the Federal Trade Commission.
Previously, these officials had appeared to be protected from political interference.
Remarks by conservative justices in those cases indicated that the court will soon reassess anti-unitary precedents.
In Trump v. Boyle, Justice Brett Kavanaugh wrote, “whether this Court will narrow or overrule a precedent … there is at least a fair prospect (not certainty, but at least a reasonable prospect) that we will do so.” And in her dissent in Trump v. Slaughter, Justice Elena Kagan said the conservative majority was “raring” to overturn Humphrey’s and finally officially embrace the unitary executive.
In short, the writing is on the wall, and Humphrey’s may soon go the way of Roe v. Wade and other landmark decisions that had guided American life for decades.
As for what judicial endorsement of the unitary executive theory could mean in practice, Trump seems to hope it will mean total control and hence the ability to eradicate the so-called “deep state.” Other conservatives hope it will diminish the government’s regulatory role.
Kagan recently warned it could mean the end of administrative governance – the ways that the federal government provides services, oversees businesses and enforces the law – as we know it:
“Humphrey’s undergirds a significant feature of American governance: bipartisan administrative bodies carrying out expertise-based functions with a measure of independence from presidential control. Congress created them … out of one basic vision. It thought that in certain spheres of government, a group of knowledgeable people from both parties – none of whom a President could remove without cause – would make decisions likely to advance the long-term public good.”
If the Supreme Court officially makes the chief executive a unitary executive, the advancement of the public good may depend on little more than the whims of the president, a state of affairs normally more characteristic of dictatorship than democracy.
There are many claims to sort through in the current era of ubiquitous artificial intelligence (AI) products, especially generative AI ones based on large language models or LLMs, such as ChatGPT, Copilot, Gemini and many, many others.
If that last statement made you sit up and take notice, you’re not alone. The “godfather of AI”, computer scientist and Nobel laureate Geoffrey Hinton, has said there’s a 10–20% chance AI will lead to human extinction within the next three decades. An unsettling thought – but there’s no consensus if and how that might happen.
So we asked five experts: does AI pose an existential risk?
Three out of five said no. Here are their detailed answers.