Away from the rarified atmosphere of international relations theories, in the mundane conference rooms and shabby offices where diplomacy is practiced daily, one cast-iron law seems to govern how we conceive of conflicts. It is not that history repeats itself, rather that we are doomed to focus on learning the lessons of the last crisis, not recognising the new lessons that are hurtling towards us.  

So the pain and guilt from Iraq prevented the US and Europe from defending the Syrian opposition against Assad a decade later (leaving the field to Russia). In turn, the UK role in that Iraq invasion was shaped by Tony Blair’s experience that controversial interventions in the Balkans and Sierra Leone had been successful and vindicated. We learn from our past experience, and then we try to squeeze current events into that mould.

Perhaps that applies even more strongly to a US President highly attuned to comparisons with his predecessors’ performance. Obama was widely criticised for not doing more to support the Iranian democracy protests in the 2009 ‘Green Movement’. So Trump made a point of promising protestors this January that ‘help is on its way’. In parallel, he still seemed to believe that, as master of the art of the deal, he alone could get the Iranian regime to capitulate in negotiations, if he amassed a big enough military threat against them.  

Why is the Middle East at war now? Partly because those two objectives were incompatible. Also because military build-ups have a momentum all of their own, and because Israel was never prepared to live with a ‘better version’ of the JCPOA (2015 nuclear deal) if a further, decisive military blow to the Islamic Republic was within reach.  

Iranians, and the country’s neighbours, are desperate to know how this will end. But, while that is the most pressing question, there is also value in looking at what this war means, and what it says about the future.  

It is too simplistic to say, as some have, that wars of choice are now the norm, and international law has been replaced by the law of the jungle. It’s clear that finding a legal justification for the attacks was not uppermost in the minds of President Trump or those around him: we have heard variously that the objective is to give Iranians the chance to overthrow their government; that Iran was on the brink of developing an inter-continental ballistic missile that could threaten the continental US; that Washington was acting in pre-emptive self-defence because the President ‘had a strong feeling’ that Iran was about to attack the US; and (from Marco Rubio) that as Israel was going to attack Iran, the US had to act to defend itself from Iran’s presumed retaliation. As legal justifications for military action in self-defence, none of these pass the most basic tests of evidence or logic. But perhaps that is the point. The current US administration, more than any before it, is unwilling to be constrained by norms or laws, let alone by institutions like the UN. If the Commander in Chief believes an action is in the US interest, he should be able to take it.  

Some see Trump’s brutal rejection of these constraints as refreshing honesty. Mark Carney rightly reminded us in his Davos speech how the international rules-based order had too often been window-dressing. And yet, in the midst of great power politics, there is still weight in the concept of legality that sits above the national level. Otherwise we would not be seeing the above-mentioned contortions from the US administration to justify their actions. International law rarely acquires its authority from enforcement. Its power comes rather from the slow, sedimentary accumulation of practice: states de facto accepting the legitimacy of certain norms before ratifying them as codified conventions, and eventually supporting institutions to oversee them.  But the first step is custom, and much international law rests on that alone: what have most states, over time, come to accept as legitimate rules of behaviour. This makes international law inherently contestable — but also resilient, because a few rogue actions cannot erase decades of accumulated practice.

After all, it’s not as if the Islamic Republic of Iran has been a great adherent to international law. As an IRGC interrogator once told me after I had pointed out his breach of international law in arresting me: ‘You’re not in Vienna now.’ The regime has for decades breached its human rights obligations, and supported terrorism, kidnapping and assassination in third countries. But breaching the law doesn’t invalidate it. When the regime in Iran does eventually fall, there will be a thirst to hold its leaders and enforcers to account. Will that be at a national level, or through an international mechanism like the ICC or a stand-alone tribunal?  

What the current war shows us is not that international law is irrelevant, but that the case for it needs to be made afresh on every occasion, and can’t just be made as an a priori argument. Too many lawyers argue from an ivory tower: because the law exists and has been enshrined, it must be obeyed. Statecraft doesn’t work like that.  The argument for abiding by international law always has to be grounded in the practical reasons for it.  Without legal backing, such campaigns lack allies and coalitions.  The perceived legitimacy of the US matters.  Without it, middle and emerging powers, those crucial players in a world dividing into camps, will be harder to enlist on issues from trade to non-proliferation. Perhaps most importantly, wars of choice legitimise attacks by other powers, including Russia and China.  

With bombs falling on Iran, European powers, including the UK, in a tricky position. As the British government has found, treading a cautious tightrope to remain supportive of allies while firm on legal boundaries leads to criticism from all sides. Sensibly, Keir Starmer has couched his concerns more around the impracticability of military operations with no clear end state than on dry legalism. But he has nevertheless been excoriated by Trump, if not as harshly lashed as Spanish Prime Minister Sanchez. If past spats are anything to go by, these fences may be mended before too long. But that is thin comfort for European leaders walking this narrow path. 

They should hold fast to their principles, nonetheless. Europe may have little to contribute to a military confrontation in the Gulf, but in any future phase that builds towards more stability, European input will be more important, not just in economic relations but in diplomacy, where law and norms matter. European powers (Britain and France, mainly) have often got it wrong in the Middle East. But at least that painful record has left them with lessons for what works and what does not. A future architecture for peace and prosperity in the Persian Gulf, just like any lasting stabilisation in Palestine and the Levant, will need underpinnings of legitimacy, not just force.  European nations, ideally speaking with one voice, can advocate for this, while respecting that regional countries are in the driving seat. That means patience and consistency, and not being blown off course by rhetorical blasts from Washington. The decline of the ‘rules-based order’ doesn’t compel a headlong rush to ‘might is right’.

Perhaps the best example of where poor planning and a casual approach to law can lead is the recent speculation about finishing the job in Iran by arming and mobilising the Iranian Kurdish groups to overthrow the regime. It’s difficult to think of a policy that would carry such meagre prospects of success and such overwhelming risks. The likely trajectory would be towards civil war, copycat conflict among the Baluchi, Arab, Azeri and other populations, a rallying of ‘Persian’ Iranians around the regime, the involvement of Turkey and the destabilisation of Iraq. Rather, Western outreach to these minority groups should be focused on how to support an orderly transition and unite with other opposition groups around a vision for a future Iranian state that respects the rights of all.  

As the air campaign continues, a historical parallel insistently raises its head: a country with its military decimated in a decisive war, but its leadership still clinging on to power; crippled by years of sanctions; its nuclear programme recently comprehensively dismantled; an international pariah that is periodically bombed by dominant Western forces, but continues to terrorise its own people. This was Iraq all through the 1990s, but sounds eerily like where we might end up with Iran. In Iraq, the pathway to that situation had been action approved unanimously by the Security Council and undertaken by a wide coalition, yet the end result was still a morass for the international community and a tragedy for the Iraqi people. As policymakers think about which lessons to learn from the past, avoiding that parallel would be a good starting point.