Introduction

The escalating conflict between Israel and Iran, marked by Israeli strikes on Iranian nuclear facilities beginning June 13, 2025, has evolved beyond a regional crisis. It represents the world's first full-scale "threshold war"—a dangerous new form of conflict where a nuclear-armed state uses military force to prevent a rival on the verge of nuclear weapons capability from crossing that threshold.¹ This dynamic, which has already resulted in hundreds of deaths in Iran and at least 24 in Israel, signals the potential collapse of traditional nuclear deterrence frameworks and sets a perilous precedent for global security.²

The "Threshold War" Dynamic: An Inherently Unstable Spiral

Unlike established nuclear rivalries (e.g., India-Pakistan), where mutual assured destruction enforces a degree of stability, the threshold war creates a vicious cycle of escalation:

• Iran's Perspective: Facing direct military strikes, Iran increasingly believes it cannot deter Israeli aggression without nuclear weapons. Every Israeli attack reinforces this conviction.
• Israel's Perspective: Israel calculates that it cannot tolerate a nuclear Iran and believes military action is necessary to delay or degrade the programme, even if it cannot permanently eliminate Iran's scientific knowledge.³

This creates a "commitment trap" where neither side can de-escalate without accepting an intolerable outcome: for Israel, a nuclear Iran capable of ending its regional military dominance; for Iran, the existential threat of regime change through continued devastating strikes.⁴

The Preventive Strike Precedent and the Erosion of Norms

Israel's operation, dubbed "Rising Lion," represents a dangerous shift from pre-emptive strikes (responding to an imminent threat) to preventive strikes (targeting a potential future capability when conditions seem favourable).⁵ Israel justified the action by citing intelligence that Iran could rapidly assemble up to 15 nuclear bombs.⁶

This action builds upon the erosion of international legal frameworks since the U.S. "War on Terror," which normalized pre-emptive warfare and drone strikes with limited consequences.⁷ The strike has had immediate counterproductive effects:

• Iran announced it was preparing a parliamentary bill to withdraw from the 1968 Nuclear Non-Proliferation Treaty (NPT), a move predicted by IAEA Director Rafael Grossi.⁸
• Scheduled U.S.-Iran nuclear talks were cancelled, with Tehran dismissing dialogue as "meaningless."⁹

By normalizing attacks on nuclear infrastructure, this precedent risks encouraging similar preventive actions by other powers (e.g., India, China, or the U.S.) against emerging nuclear programs globally.¹⁰

Escalation to Regional Conflagration

The initial Israeli strike triggered immediate and sustained retaliation:

• Iran launched waves of hundreds of drones and missiles beginning June 13, followed by strikes on energy infrastructure and military bases.¹¹
• The Houthis in Yemen joined by firing ballistic missiles at Tel Aviv.¹²
• Notably, Iran's traditional "axis of resistance" proxies—Hezbollah, Hamas, and Iraqi militias—remained relatively quiet, having been degraded by recent Israeli actions. This degradation removes Iran's conventional forward deterrent, potentially making nuclear weapons appear as its only reliable security guarantee.¹³

Iranian President Masoud Pezeshkian vowed that destroyed nuclear facilities "would be rebuilt," underscoring how preventive strikes can solidify, rather than deter, nuclear ambitions.¹⁴

The Collapse of Deterrence and Diplomacy

Threshold wars break the core assumptions of traditional nuclear deterrence theory:

• Asymmetric Vulnerability: Iran cannot fully deter Israel because it lacks confirmed weapons; Israel cannot rely on deterrence to stop Iran's advancing program.
• "Use It or Lose It" Calculus: Israel faces a shrinking window for preventive action, while Iran faces incentives to race toward a nuclear deterrent before more strikes occur.¹⁵

The failure of external mediation is stark. U.S. President Donald Trump, who initially opposed military action, pivoted after strikes began, warning on Truth Social: "There’s more to come. A lot more," and lamenting that Iran did not accept his earlier diplomatic ultimatum.¹⁶ This illustrates how quickly diplomacy collapses once threshold wars commence.

Global Implications and a Catastrophic Precedent

The international response has effectively normalized aggression against nuclear facilities. While European leaders called for "maximum restraint," none condemned Israel's initial attack. Russia and China issued condemnations but took no concrete action. The UN Security Council produced only statements of "concern."¹⁷

The implications are profound:

1. Proliferation Incentives: A successful Iranian push for nuclear weapons following strikes could encourage other threshold states (e.g., Saudi Arabia) to rapidly and secretly pursue their own capabilities.¹⁸
2. Preventive Strike Cascades: Successful Israeli strikes could incentivize similar preventive actions in other nuclear hotspots, unraveling the global non-proliferation regime.
3. New Nuclear Governance: The world may be moving from an era of deterrence-based stability to one defined by cycles of preventive strikes and accelerated proliferation—a scenario far more unstable than the Cold War.¹⁹

Conclusion

The Israel-Iran threshold war is not merely another Middle Eastern conflict. It is a strategic watershed that demonstrates the fatal flaws in relying on military prevention to enforce non-proliferation. By collapsing deterrence, discrediting diplomacy, and legitimizing attacks on nuclear infrastructure, it sets a catastrophic precedent that threatens to destabilize global nuclear order for decades to come. The international community's tepid response suggests that the norms which have constrained nuclear conflict since 1945 are eroding, paving the way for a more dangerous and unpredictable future.