Diplomatic engagement is capable of preventing armed conflict between the United States and Iran despite their fundamental disagreements

What's this about?

People disagree about whether talks can stop a war between the United States and Iran.

The key question asks if talks can work despite deep fights between both sides.

What supporters say

• Help from a third side can work when both sides want peace and can keep their deals.
• The 2015 nuclear deal set real limits on Iran’s bomb fuel, stores, and tools.
• Checks by global experts found that Iran followed key parts of the deal at first.
• Secret or direct talk lines can calm fast crises by clearing up each side’s plans.

What critics say

• The main fight goes far beyond nuclear arms and includes many other security issues.
• Deals can fall apart when new leaders take power and change course.
• Talks did not stop an armed clash after the United States killed Iran’s top army leader in 2020.

How to read this

The number of points on each side does not show who is right; strong proof matters more than a long list.

The bottom line

The evidence shows that talks can lower some risks and stop certain crises.

But talks cannot fix the whole United States–Iran fight or ensure that deals will last.

The claim that diplomacy can prevent armed conflict between the United States and Iran is partly supported, but only in a limited and conditional sense. Negotiations have reduced specific risks, yet they have not overcome the wider rivalry or guaranteed that agreements will survive political change.

The case for

The strongest evidence comes from the 2015 nuclear agreement, known as the JCPOA. It placed limits on Iran’s uranium enrichment, nuclear stockpiles and centrifuge activity. Reports from the International Atomic Energy Agency found that Iran implemented and inspectors verified important commitments during the agreement’s early period. The deal lengthened the warning time before a possible nuclear escalation and reduced pressure for preventive military action 1 (see Figure 1).

That record shows that diplomacy can turn deep political disagreement into practical limits on dangerous activity. The United States and Iran did not resolve their broader conflict, but they established rules that constrained one major path toward confrontation.

Diplomatic communication can also help manage sudden crises. Direct or indirect channels, reciprocal steps to reduce tensions and third-party mediation can clarify intentions and prevent incidents from escalating. Research on mediation similarly finds that it can improve efforts to manage conflicts when both sides have reasons to cooperate and when agreements can be implemented 23.

This support is strongest for a narrower claim: diplomacy can prevent or contain particular escalatory episodes. It is weaker evidence that engagement can settle the entire strategic conflict between Washington and Tehran.

The case against

Diplomacy and communication did not prevent the direct military confrontation surrounding the 2020 killing of Iranian commander Qassem Soleimani. That episode showed that negotiations are not enough when leaders believe immediate security or political needs require military action 4. It does not prove that communication had no moderating effect, but it does show that diplomacy cannot guarantee restraint.

The JCPOA also revealed how vulnerable agreements can be to political change. The United States withdrew from the agreement in 2018 and restored sanctions. Iran then gradually reduced its own compliance. An agreement may impose effective limits while it is in force, yet still fail if political leaders are unwilling or unable to preserve it 5.

The nuclear deal also covered only one part of the wider dispute. Tensions over sanctions, missiles, Iran’s regional partners and activities, and the security of Iran’s political system remained largely unresolved. Those disagreements created other routes toward escalation, meaning that nuclear diplomacy alone cannot support the broad claim that armed conflict between the two countries has been prevented 6.

There are also limits to what the available evidence can establish. It documents negotiated restraints, the collapse of an agreement and later confrontation, but it does not show precisely how much diplomacy changed the risk of war compared with deterrence, sanctions, military signals or other factors. There is limited direct evidence about the outcomes of specific U.S.-Iran backchannel efforts, and no systematic comparison of crises in which engagement succeeded with those in which it failed.

The bottom line

The evidence favors a qualified version of the claim, but only with low confidence as a general proposition. Diplomacy has demonstrated that it can reduce the likelihood and severity of particular confrontations, especially when agreements are verifiable, both sides have incentives to comply and leaders support implementation.

It has not demonstrated an ability to guarantee lasting peace between the United States and Iran. The JCPOA’s verified early success and later collapse are not contradictory: diplomacy can work within a defined issue and period while failing to survive leadership changes or spill over into other disputes.

The more defensible conclusion is that sustained, verifiable and politically durable engagement can create additional chances to prevent escalation. Diplomacy is a risk-reduction tool, not a substitute for deterrence or a solution to the underlying rivalry.