Why Diplomacy Worked Better than Force in Dealing with Iran
The 2015 nuclear deal imposed limits, inspections and time. Military strikes merely delayed the problem, and only for a matter of months. A commentary by Ambassador Pasquale Quito Terracciano
International law still matters, or at the very least it should. The same is true of diplomacy. This is not a sentimental attachment to old formulas. It is a practical judgment based on outcomes. War does not solve the problem it claims to address. Diplomacy, when it is serious and verifiable, often does more.
That is the proper way to assess the confrontation with Iran. The question is not whether diplomacy sounds preferable in theory. It is whether the use of force has produced a better result. Has military action left the region, the US and its allies in a safer position? The answer is no.
The clearest comparison is with the JCPOA, the Joint Comprehensive Plan of Action, the 2015 agreement between Iran and the major powers over Tehran’s nuclear programme. That agreement remains the best available demonstration that negotiation can achieve results that are both more durable and more predictable than coercion.
This is not simply an argument about western values, though those values should matter in foreign policy. It is a broader point about effectiveness. When states abandon negotiation in favour of force, they often end up in a weaker strategic position. Russia offers one example. Iran offers another.
For that reason, the burden of proof should not lie with those who defend diplomacy. It should lie with those who insist there is no longer time or space for negotiation and that military action is the only credible answer. In Iran’s case, events have not supported that claim.
After the first round of attacks on Iran last June, Donald Trump said the strikes had been a success and that Iran’s nuclear programme had been effectively crippled. Yet within six to eight months, Israel and the US judged it necessary to strike again, pursuing essentially the same objective.
That is a measure of the limits of force. Military action can delay Iran’s programme, but not settle the issue. If another intervention is needed after eight months, then eight months is all war has really bought.
That is the point against which diplomacy should be measured. What did the JCPOA offer instead?
Here it is worth relying on technical expertise rather than political slogans. The IAEA, the International Atomic Energy Agency, is the UN body responsible for monitoring nuclear activities and verifying compliance with nuclear commitments. Its assessment was that the JCPOA provided at least a two-year cushion of safety.
The agreement did so through specific and enforceable constraints. It capped Iran’s stockpile of low-enriched uranium at 300 kilograms and limited enrichment to 3.67 per cent, far below weapons-grade level. It also required the removal of more than two-thirds of Iran’s centrifuges, the machines used to enrich uranium.
These details matter. Uranium can be enriched for civilian purposes, including energy production. But if a country already has a substantial stockpile of uranium and a large number of centrifuges, it can move much more quickly towards the higher levels of enrichment required for weapons use. That was the central concern.
The JCPOA addressed exactly that risk. By limiting both Iran’s stockpile and its enrichment capacity, it extended the so-called breakout time — the period Iran would have needed to produce enough fissile material for a weapon if it chose to abandon the agreement.
According to the IAEA’s technical judgment, that period was pushed out to roughly two years. Just as importantly, the agreement subjected Iran’s programme to inspections and international monitoring.
That makes the contrast with military action unusually clear. The current logic is one of periodic disruption: strike when Iran appears to be nearing a dangerous threshold, push the programme back, then wait until the threat rebuilds. But if that cycle has to be repeated within eight months, then the strategic gain is modest and temporary.
It is certainly less than the margin created by an agreement that imposed constraints, allowed inspections and bought at least two years of relative security.
The JCPOA also provided something that force cannot: visibility. It allowed inspections. It generated information. It reduced the room for conjecture.
The agreement remained in place from 2015 until the US withdrawal in 2018 under President Donald Trump. After that decision, the system of inspections and structured verification was progressively hollowed out. What followed was not greater certainty but less: more assumptions, more intelligence assessments, more inference and fewer shared facts.
That matters strategically as much as diplomatically. A policy based on recurring strikes and diminishing transparency does not create lasting deterrence. It increases instability, raises the risk of miscalculation and leaves allies uncertain about both American intentions and American reliability.
Nor is the cost confined to security policy. Destabilising a region as important as the Gulf carries obvious economic consequences. It fuels doubts among regional partners about the solidity of US protection. It also creates the conditions for renewed inflationary pressure, especially through energy markets, at a moment when the global economy can ill afford another shock.
This is why diplomacy deserves another chance, not as an act of naïveté but as an exercise in realism. The question is not whether negotiation is flawless. It never is. The question is whether it performs better than the alternative.
In the case of Iran, the answer is clear. The negotiated framework of the JCPOA imposed stricter limits, delivered greater oversight and bought more time than the episodic use of force has managed to achieve.
Diplomacy did not solve the problem once and for all. But it contained it better than war. In international affairs, that is often the most meaningful standard of success.
This commentary is based on remarks by Pasquale Terracciano at an IEP Bocconi event held at the EGEA Bookshop on March 19.
IEP@BU does not express opinions of its own. The opinions expressed in this publication are those of the authors. Any errors or omissions are the responsibility of the authors.
