The UK government’s top legal adviser has raised questions over whether Israel’s actions in Iran are lawful, according to a source familiar with discussions inside the government.
The source suggested to Sky News that Attorney General Richard Hermer’s thinking, which has not been published, complicates the UK’s potential involvement in the Iran-Israel conflict.
If the attorney general deems Israel’s actions in Iran to be unlawful then the UK is restricted in its ability to help to defend Israel or support the United States in any planned attacks on Iran.
Speaking on condition of anonymity, the source said that the attorney general’s concerns limit UK involvement in the conflict “unless our personnel are targeted”.
US President Donald Trump is currently weighing up his options for Iran and has repeatedly suggested the US could get involved militarily.
This would likely involve the use of US B-2 bombers to drop bunker-busting bombs to destroy Iran’s nuclear facility built deep into the side of a mountain at Fordow.
These B-2 bombers could be flown from the UK base at Diego Garcia in the Indian Ocean, strategically close to Iran.
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The US could also choose to fly them the far greater distance from the US mainland.
Under a longstanding convention, the UK grants permission to the US for the base to be used for military operations.
The US military could also request the use of the UK military base in Cyprus, for refuelling planes.
Any refusal by the British could complicate US military action and, diplomatically, put pressure on the trans-Atlantic relationship.
Israel’s justification
Israel has justified its war by claiming that Iran poses an “imminent” and “existential” threat to Israel.
Prime Minister Benjamin Netanyahu has cited his country’s own undisclosed intelligence claiming Iran was on the brink of obtaining a nuclear weapon.
The Israeli government also claimed, without publishing evidence, that Iran was planning an imminent attack on Israel.
They also cited the recent International Atomic Energy Agency (IAEA) report which concluded that Iran had been “less than satisfactory” in “a number of respects” on its international compliance over its nuclear activities.
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It is not clear what aspect of Israel’s justification for military action the attorney general has concerns over.
The Attorney General’s Office has told Sky News: “By long standing Convention, reflected in the ministerial code, whether the law officers have been asked to provide legal advice and the content of any advice is not routinely disclosed.
“The Convention provides the fullest guarantee that government business will be conducted at all times in light of thorough and candid legal advice.”
The UK armed forces have previously rallied to help defend Israel from Iranian missile and drone strikes when the two sides engaged in direct confrontation last year.
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In April 2024, RAF typhoon jets shot down drones fired from Iran.
The UK military was also involved in efforts to defend Israel from a ballistic missile attack in October 2024.
But the UK has not been involved in the current conflict, which began when Israel targeted Iranian nuclear facilities and scientists as well as more definitive military targets such as missile launchers and commanders.
The UN’s nuclear watchdog has previously raised concerns about any attack against nuclear facilities because of the inherent danger but also the legality.
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A number of resolutions passed by the IAEA’s general conference has said “any armed attack on and threat against nuclear facilities devoted to peaceful purposes constitutes a violation of the principles of the United Nations Charter, international law and the Statute of the Agency”.
Israel believes that Iran’s nuclear programme has a military use, which makes it a legitimate target.
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It believes the regime is aimed to enrich uranium to develop nuclear weapons.
Tehran, however, has always insisted its nuclear programme is for civilian use.
The International Commission of Jurists (ICJ) has also condemned Israel’s use of armed force against Iran as a violation of the United Nations (UN) Charter and international law.
Interpretations of International Law
Different countries adopt varying interpretations on the use of force in response to future attacks.
The first legal position is that nations can act preventatively to deflect threats.
The second is that they can act to deflect future armed attacks that are imminent.
The third is that states can only act to deflect attacks that have occurred.
That third position is generally considered to be too restrictive and the first as too broad.
The grey area lies with the second position, and it rests with the definition of “imminent”.
The concepts of ‘proportionality’, ‘necessity’ and ‘imminence’ are key considerations.
International law scholars have told Sky News that Israel may pass the ‘proportionality’ test in its actions against Iran because its targets appear to have been military and nuclear.
But whether there was the ‘necessity’ to attack Iran at this point is more questionable.
The attorney general would likely be considering the key legal test of the ‘imminence’ of the Iranian threat against Israel – and whether it is reasonable to conclude that an attack from Iran was “imminent” – as he weighs the legal advice issued to UK Prime Minister Sir Keir Starmer.
There is always nuance with legal advice, judgements rest on a variety of factors and advice can evolve.
In the run up to the 2003 Gulf War, the US and UK justified their action by arguing that Saddam Hussein possessed Weapons of Mass Destruction – a claim that turned out to be wrong.
The then-attorney general’s advice, which evolved, was central to Tony Blair’s decision to join President Bush in attacking Iraq.
