The dust has barely settled on the 12-day conflict between Israel and Iran that ended on June 24, 2025, but its implications for global nuclear governance are already becoming clear. What began with Israeli strikes on Iranian military and nuclear sites on June 13, killing key nuclear scientists and military commanders, escalated into an intense exchange that left at least 610 Iranians and 28 Israelis dead before a fragile US-brokered ceasefire took hold.

This crisis marked the world’s first full-scale example of what I call a “threshold war” – a new and terrifying form of conflict where a nuclear weapons power seeks to use force to prevent an enemy on the verge of nuclearization from crossing that line. The precedents set during these 12 days may have permanently altered the landscape of nuclear proliferation and deterrence.

The anatomy of a ‘Threshold War’

More than 200 Israeli fighter jets hit over 100 nuclear and military facilities across Iran in the opening salvo of Operation Rising Lion. Israel justified its actions by claiming Iran could rapidly assemble up to 15 nuclear bombs – a preventive strike aimed at eliminating not an imminent threat, but a future capability.

The escalation was swift and brutal. Iran retaliated with hundreds of ballistic missiles against Israeli cities, with both nations trading strikes daily. The conflict took a dramatic turn on June 21 when the US military struck three of Iran’s nuclear facilities – Natanz, Fordow, and Isfahan – using bunker-buster munitions in what President Trump later claimed would prevent Iran from building bombs “for a very long time.”

Yet an early US intelligence assessment suggested the strikes did not destroy the core components of Iran’s nuclear program and likely only set it back by months. This sobering reality underscores the fundamental flaw in the threshold war logic: military action can delay but not eliminate nuclear knowledge.

The ceasefire that almost wasn’t

The June 24 ceasefire itself illustrated the inherent instability of threshold conflicts. The phased 24-hour process was initially violated by both Israel and Iran. President Trump’s public frustration – telling Israel to “calm down. Do not drop those bombs. Bring your pilots home, now!” – revealed how quickly these conflicts can spiral beyond even superpower control.

Nuclear governance in ruins

The most alarming development came in the conflict’s aftermath. The US Senate rejected a Democrat-pushed resolution aimed at reining in President Trump’s ability to use military action against Iran without congressional approval, while Iranian President Masoud Pezeshkian claimed his country had achieved a ‘historic victory’ despite the devastating losses.

More ominously, Iran’s parliament is now considering legislation to withdraw from the Nuclear Non-Proliferation Treaty – a move that would formalize what this conflict has already achieved in practice: the collapse of the diplomatic framework that has governed nuclear proliferation for over half a century.

The commitment trap realized

The dynamics of this conflict perfectly illustrate what strategists call the commitment trap – where both sides face escalating costs but cannot back down. Both Israel and Iran emerged from this conflict more committed to their respective paths. Israeli Defense Minister Israel Katz instructed the military to prepare an enforcement plan against Iran suggesting Israel views military action as an ongoing necessity rather than a one-time solution.

For Iran, the calculation has fundamentally changed. The destruction of its nuclear facilities, which Iran has vowed to rebuild combined with the degradation of its proxy forces, leaves nuclear weapons as perhaps the only reliable deterrent against future Israeli strikes. The threshold war, intended to prevent nuclearization, may have made it inevitable.

Setting global precedents

The international response – or lack thereof – sets a catastrophic precedent. The US ambassador to the UN defended the strikes as fulfilling “our narrow objective: to degrade Iran’s capacity to produce a nuclear weapon,” essentially legitimizing preventive attacks on nuclear infrastructure. If this becomes the new norm, we can expect similar actions elsewhere, accelerating rather than preventing proliferation.

The comparison to North Korea is instructive. Despite decades of threats, Pyongyang’s nuclear arsenal makes it essentially immune to preventive strikes. Iran’s leaders have surely absorbed this lesson: the window between being a threshold state and a nuclear weapons state is when the state is most vulnerable.

A new nuclear disorder

As the smoke clears from this 12-day conflict, we face a transformed nuclear landscape. The threshold war model has proven itself to be exactly what critics feared – a recipe for escalation that makes nuclear proliferation more, not less, likely. Traditional deterrence frameworks, already strained, have been replaced by a dangerous new logic where preventive war becomes When military action becomes the primary tool for managing nuclear ambitions, the incentive for threshold states is clear: cross the nuclear threshold as quickly and quietly as possible, before the next preventive strike arrives.self-defeating prophecy.

The Iran-Israel threshold war of June 2025 will be remembered not for preventing nuclear proliferation, but for accelerating it. 

We have entered a new era of nuclear competition, one where the rules that kept the Cold War cold no longer apply. The question now is not whether other threshold wars will follow, but when – and whether the international community can develop new frameworks before the next conflict spirals beyond control.

Farah N. Jan is Senior Lecturer in International Relations at the University of Pennsylvania.