Iran’s nuclear ambitions and Israel’s right to defend itself
Allies backing Israel should stress the uniqueness of the threat posed by Iran to Israel
Israel has nothing to boast about when it comes to its activities in the Occupied Territories, but its attacks on Iran’s nuclear sites raise more complex issues of law and legitimacy.
While academics and other legal professionals and a number of national governments have condemned these attacks as contrary to international law, the EU’s High Representative, and key allies of Israel in Europe and beyond have not, instead showing political support and perhaps legal endorsement for Israel’s actions.
Whether they choose the narrative of legitimacy or legality, allies should stress the exceptional and perhaps unique nature of the threat to Israel posed by Iran, lest they be accused of backing an open-ended and self-judging approach to self-defence.
Iran does not recognise Israel, has called for its destruction, and for decades has been working to develop the technical know-how to produce nuclear warheads.
Iran insists that its nuclear research and development activities are entirely for peaceful purposes, and denies any intention of developing nuclear weapons. Uranium for civilian nuclear purposes requires enrichment of about 4%. Iran has enriched uranium to 60% - inexplicable in terms of Iran’s declared aim of developing nuclear power for civilian purposes, but entirely explicable if the aim is to achieve enrichment to the 90% level necessary to produce nuclear-weapons grade material.
On the night of the 12/13 June Israel launched its military operation “Rising Lion” against facilities vital to Iran’s nuclear programme. Iran responded with attacks on Israel. A number of legal scholars at once condemned Israel’s attack on Iran as aggression. Turkey’s foreign ministry condemned Israel’s attacks in the strongest terms as a violation of international law, as did Saudi Arabia, and China, Iran’s largest energy customer. It is reported that 21 Arab, Muslim states have condemned Israel’s attacks.
The threat posed to Israel by Iran’s nuclear programme
Israel Prime Minister Benjamin Netanyahu sought to justify Israel’s military action with the claim he had acted to pre-empt a secret Iranian programme to build a nuclear bomb, claiming Tehran already had the capacity to build nine nuclear bombs.
On 12 June the Board of Governors of the International Atomic Energy Agency (IAEA) recorded their view that failures by Iran in its international obligations prevented the Agency offering any assurances that Iran’s nuclear programme is exclusively peaceful. They also referred to the rapid accumulation of highly enriched uranium by Iran, to the fact that Iran is the only State without nuclear weapons that is producing such material, and to the fact that the Agency could not verify that there had been no diversion of nuclear material to nuclear weapons.
Asked in April when Iran might be capable of weaponizing nuclear warheads, Director-General of the IAEA, Rafael Grossi Grossi said: “ It would be, you know, a matter of months, not years.”
Also in April, France’s Minister for Europe and Foreign Affairs stated bluntly that “Iran is in the process of acquiring nuclear weapons”, and referred to Iran exceeding by more than 30 times the limit on enriched uranium it had pledged to respect in its agreement of 2015 with the UK, China, France, Germany, Russia, and the US.
Israel’s allies around the world have offered cautious support
The response of key allies of Israel to its attacks on Iran’s nuclear sites has been to call for de-escalation on the part of Israel and Iran, rather than to condemn Israel for breaches of international law.
The EU’s High Representative, Kaja Kallas, while calling on “on all sides to abide by international law”, declared that “the EU has always been clear that Iran must never be allowed to acquire a nuclear weapon”. She added that “lasting security is built through diplomacy, not military action.”
President Macron also urged restraint, but said that Iran bore a heavy responsibility for destabilisation of the Middle East by pushing ahead with an unjustified nuclear programme.
Germany’s Chancellor Friedrich Merz referred to Israel’s right "to defend its existence," which has been interpreted in Israel as backing for Israel’s attack.
It is reported that a majority of EU Member States support Israel’s right to defend itself against Iran by striking its nuclear sites.
The response of Canada’s Mark Carney was to reaffirm Israel’s right to defend itself and to ensure its security, and to call on all parties to exercise maximum restraint.
The UK’s Keir Starmer expressed the UK’s grave concerns over Iran’s nuclear programme, referred to UK recognition of Israel’s right of self-defence, and urged all sides to de-escalate and negotiate.
Australia’s foreign minister referred to Israel’s right to defend itself, did not answer questions asking whether Israel’s attacks were contrary to international law, and urged restraint on all sides.
The G7 (Canada, France, Germany, Italy, Japan, the UK, and the US) issued a short statement on June 17 “on recent developments between Israel and Iran”. It contained a reaffirmation of Israel’s right to defend itself, added the words “We reiterate our support for the security of Israel,” and the words “We have been consistently clear that Iran can never have a nuclear weapon.” (Despite Japan endorsing this statement, it should be noted that on June 13, Japan’s Prime Minister had described Israel’s attack as "totally intolerable" and "extremely regrettable".)
Whether allies are backing the legality of Israeli action as well as its legitimacy is not yet clear
Most of the statements referred to above from Israel’s allies seem to back Israel’s right to take military measures against Iran in order to block or delay its development of nuclear weapons. It is not clear whether this backing amounts to saying Israel has acted legitimately and in accordance with international law, or to saying that Israel is acting legitimately but not necessarily in accordance with international law. And that is not a contradiction in terms – see the final section of this blog.
Iran was not threatening a literally imminent nuclear attack on Israel – but perhaps any future attack was imminent enough to justify preventative action
If allies are backing Israel’s legal position, they need to meet the criticism that Israel’s attacks on Iran’s nuclear sites are an unlawful use of force prohibited by Article 2(4) of the United Nations Charter, and that the international law of self-defence cannot be stretched to justify an attack on Iran which cannot be described as in progress or imminent.
The starting point for analysis is Article 51 of the UN Charter, which states that “Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations.”
Some read this text as authorising self-defence only in response to an armed attack, but this is an unduly narrow reading that leaves out of account the reference to the “inherent right” of self-defence, which is a reference back to pre-existing customary law which does countenance pre-emptive self-defence in some circumstances.
The advice given in March 2003 by then Attorney General Lord Goldsmith to UK Prime Minister Tony Blair on the legality of military action against Iraq is widely regarded as containing an accurate statement of the international law of self-defence.
Lord Goldsmith says that self-defence is only permissible if there is an actual or imminent threat of an armed attack. The most obvious objection to reliance by Israel on self-defence to justify its attacks on Iran is that Iran’s development of nuclear capabilities neither amounts to an armed attack, nor presents a situation when an armed attack is imminent.
At the time of Israel’s attack on Iran, any attack by Iran on Israel must have been at least months away, and it could not have been said with certainty that Iran would attack Israel with nuclear weapons as soon as it acquired them, or indeed at all. Put this way, a nuclear attack by Iran does did not seem literally “imminent” at the time Israel attacked Iran’s nuclear sites.
But that way of framing the issue of imminence might be inadequate, given the exceptionally high risk that Iran would develop nuclear warheads and would use them against Israel sooner rather than later.
The concept of what is imminent depends on the circumstances
Lord Goldsmith said in the legal advice referred to above, “The concept of what is imminent may depend on the circumstances.” He added that “Different considerations may apply… where there is a threat of an attack by nuclear weapons.”
A state facing a risk of nuclear attack may be unsure whether its last opportunity for effective defensive action is yet to arrive, or has passed, because first use of nuclear weapons by one antagonist may deprive the other of the ability to defend itself.
For Israel, this predicament has been magnified many times over by the fact that Iran’s leadership do not recognise Israel’s right to exist and regard the destruction of Israel as a legitimate foreign policy aim.
If Israel were to miss its last opportunity to destroy Iran’s nuclear capability with proportionate conventional military strikes on Iran’s nuclear facilities*, the result could be the destruction of Israel, which is a small and densely populated country.
*I offer no assessment of the proportionality of Israeli military action
A realistic approach to imminence in this unique context
Perhaps the right approach to imminence in this context, is to ask whether a future attack by Iran was sufficiently imminent to justify preventive action by Israel, given the nature and scale of the threat it faced, and the need for any defensive military action to come at a stage when it might still have some prospects of success.
If what I am trying to do is to tentatively state the current law of self-defence in an exceptional and probably unique context such as that under discussion, my statement is this – that one state is entitled to use proportionate force against another state if the conduct of the second state indicates that it will use nuclear weapons against the first state at its earliest opportunity in order to destroy that state and its claim to statehood, and if the point has been reached where delay by the first state could deprive it of the opportunity to defend itself and to survive as a state.
Israel’s attacks on Iran’s nuclear sites must have been the only response likely to avert a future attack by Iran
I am not forgetting a further requirement of the law of self-defence – that the use of force to pre-empt an imminent attack must be the only means available of averting that attack.
No doubt it can be said that Israel could and should have placed its faith in further indirect talks between Iran and the US, with a sixth round of talks actually scheduled to take place in Oman on 15 June 2025. The talks might have led to arrangements similar to the Joint Comprehensive Plan of Action which was agreed between Iran, the UK, China, France, Russia, the US, and Germany in 2015.
Yet the recent findings of the IAEA, referred to above, about Iran’s breaches of its international obligations and stockpiling of enriched uranium at levels way above those needed for a civil nuclear programme, provided grounds for doubting Iran’s good faith at that time.
I offer no assessment of the factual issues raised by the above test for imminence, nor on the question whether progressing further talks prior to Israel’s military strikes would have set Iran on a different course that that described by the Board of Governors of the IAEA on 12 June and referred to above. Assessment of the complex factual matrix around Iran’s nuclear programme and the consequences of taking military action or not taking military action, is a matter for Israel in the first instance, and its allies and the court of world opinion thereafter.
Legitimacy can point the way to legality
At time of writing the UN Security Council is scheduled to meet on June 20 to be briefed Israel’s attacks on Iran. Key allies of Israel, including the UK, have signalled that it was legitimate for Israel strike Iran’s nuclear sites in order to defend itself. To move from the position of legitimacy to that of legality may be but a short step, and the UK and others might feel able to take that step. The UK has taken that step in the past, in respect of humanitarian intervention, which is regarded by more countries as legitimate than as lawful. I am not suggesting for one moment that Israel can rely on the doctrine of humanitarian intervention. Rather that if Israel’s allies are convinced that Israel’s response to Iran’s nuclear programme was legitimate, they might also back its legality in the narrow, exceptional and perhaps unique circumstances in which Israel has found itself vis-à-vis Iran.
Derrick Wyatt, KC is Emeritus Professor of Law at the University of Oxford and a former barrister. He taught EU Law, International Law, and Constitutional Law at Oxford, argued cases before the EU Courts, and advised businesses and governments.