The Future of Global Security: The Unraveling of Deterrence
As the “Epic Fury” operation strikes Iran since February 28, 2026, the proliferation of armed conflicts signals the end of a certain idea of deterrence. From Ukraine to Gaza, from the Caucasus to the Middle East, something has gone awry in the security architecture that prevented the return of wars of conquest since 1945. Not a third world war identical to the first two, but something potentially more insidious: a series of conflicts that no one seems able to contain anymore.
Since 1945 and the first use of nuclear explosives, a belief has structured Western strategic thinking: the existence of these “absolute weapons” makes any war of conquest between major powers unthinkable, rendering the territory of nuclear-armed states inviolable. These states could only confront each other indirectly in limited wars, whose intensity would never reach the hyperbolic violence of the first two world conflicts.
However, this certainty has cracked. By invading Ukraine, a country whose independence and security it had guaranteed under the Budapest Memorandum in 1994, Russia used its atomic arsenal as a shield (without risking direct U.S. involvement) to conduct a conventional war of conquest. This Russian invasion has caused a profound disruption in the mechanisms of deterrence, the consequences of which may not have been fully diagnosed.
A Shift in Threshold
The scope of what is possible under the “nuclear umbrella,” without triggering its collapse, has significantly increased. The war in Ukraine showed that a high-intensity conventional confrontation, pursuing explicit territorial annexation goals, could unfold without the nuclear threat being activated either by the aggressor to protect its gains or by states supporting Ukrainian defense to end it.
The concept of a nuclear threshold, as theorized in 1960, implied a clear line beyond which atomic war became certain. Since the war in Ukraine, this concept can no longer be strictly understood. In reality, behaviors follow more complex mechanisms: there is an area of uncertainty, an intermediate space where an infinite number of hostile acts remain possible without automatically leading to the ultimate escalation.
In other words, an increase in the threshold is observed where the behavior of certain actors becomes intolerable. And it is precisely this increase that opens a window of opportunity to “revisionist powers,” i.e., those wishing to alter the rules of the system in their favor.
For example, by using force to annex new provinces, disregarding a cardinal principle of the United Nations: the inviolability of borders. According to this principle, borders cannot be altered by force, and any modification can only happen within existing administrative boundaries. This principle had been mostly adhered to in seventy years (except for rare exceptions such as Tibet acquired by China in 1950, Kashmir, the border between the two Koreas, the Israeli-Arab wars, Northern Cyprus).
The Resurgence of Wars of Conquest
We are witnessing the most serious risk here: not a Third World War deliberately declared by a power or group of powers, leading to total nuclear war, but a proliferation of simultaneous conventional conflicts draining American capabilities and will to react, which could be termed a “world war under the threshold” (i.e., not initially provoking the use of nuclear weapons).
Over the past five years, the most significant ruptures have come from the nuclear powers themselves. Russia attempted to subdue Ukraine through a lightning offensive and formally annex five provinces, before engaging in a protracted conflict with enduring consequences for the European order. Israel, an undeclared nuclear power, responded to the Hamas attack on October 7, 2023, with unprecedented military operations in Gaza, Lebanon, Syria, against the Houthis in Yemen, and finally, against Iran, following its doctrine of “disproportionate response.” The United States, far from being a mere spectator of the system’s deregulation, has become one of the agents: the operation in Iran was launched without a UN mandate or consultation with Congress, and Washington openly threatens NATO members, thereby undermining the institutions it had helped establish. The guarantor of the previous order, tired of funding the alliance, has initiated a brutal reform that disrupts its structure and threatens to destabilize it.
Other conflicts, devoid of nuclear arsenals, have been launched not without correlation with these confrontations. In September 2020, Azerbaijan launched its first victorious offensive against Armenia, gradually leading to the disappearance of the Republic of Artsakh and the exile of over 100,000 Armenians, with no international community intervention to prevent this exodus. These conflicts are compounded by wars between Cambodia and Thailand, India and Pakistan, and Pakistan and Afghanistan. These situations demonstrate that the resurgence of limited local wars was not incidental but a significant trend, adding to the insurgency of previous decades.
While not all these wars have led to significant border changes, neither the United States nor its strategic competitors can regulate them all simultaneously. The United States could once balance all regions and tensions through external intervention (traditionally called offshore balancing), but the multiplication of emergencies and conflicts no longer allows them to act sufficiently with a limited budget. The proliferation of conflicts highlights the increased difficulty in managing them, leaving much more room for local actors to alter their relationships with neighboring states.
Especially, Russia has shown other revisionist powers that economic sanctions can be absorbed, Western war effort has industrial and political limits, and nuclear protection offers a broader range of conventional action than previously thought. All of this serves as an incentive, in the precise sense given by game theory, to use force to reshape territory and power balances. This could even challenge the very nature of the international system.
When Conflicts Threaten to Merge
In 1951, Raymond Aron, in “The Century of Total War,” noted that American strategists of the immediate post-war period had only considered two scenarios: an armed peace without direct conflict or total war leading to nuclear confrontation. According to him, they overlooked a third, “limited hot wars” like the Korean War in 1950, which caught America off guard.
Despite the terrible losses they sometimes caused, none of these “limited hot wars” degenerated into a conflict involving two directly intervening coalitions. Foreign interventions, like those of the Soviet Union and China in favor of North Vietnam, had to be discreet or limited to defensive aid to protect the ally’s territorial integrity.
Nuclear deterrence had so far confined local wars to the territory of the states involved. But the multiple, distributed, intense conflicts we are witnessing have taken on such a dimension that the possibility of creating an integrated chain of conflicts, where all “local hot wars” generate one inseparable and massive conflict, akin to the global conflicts of the twentieth century, now exists.
To draw a metaphor from the field of electricity, during the Cold War (1947-1991) and the period of American power monopoly, conflicts operated “in parallel” on the international circuit. Each could erupt or subside independently of others, without disrupting the overall system. A short circuit in one area did not affect the rest.
Our time might be reinstalling them “in series”: conflicts are now interconnected, so that each new hotspot amplifies the previous ones and increases the burden on the entire circuit.
Avoiding Escalation: What Order to Uphold?
What would happen then if a significant number of conflicts were to escalate in series? No power would be able to manage the local conflicts by projecting sufficient power.
Designed theoretically to fight two major wars simultaneously, the U.S. military can in practice only engage in one at full intensity. The United States is now paying the price for its global preeminence: it must be strong in all areas at once, while each of its adversaries only needs to dominate its region.
This structural asymmetry lies at the heart of the risk of serial conflict escalation: a single additional crisis, in Taiwan, the Gulf, or the Indian subcontinent, would place Washington in a state of strategic overload, unable to contain all tensions simultaneously.
Europe, still unsure of the direction to take between transatlantic loyalty and strategic autonomy, is not united enough to replace the United States. China, despite its undeniable rise in power, lacks both the means (blue-water navy, sufficient foreign bases) and the will to intervene in conflicts (its discretion in the Iran conflict shows a preference for solving problems related to its energy supply at lower cost through other means).
A world without a regulating power would be a world where the collapse of deterrence could truly manifest: the creation of a chain of conflicts that could perhaps usher in a return to the hyperbolic violence of the first two world conflicts. Once unleashed, uncontrollable violence could jeopardize the security of nuclear-armed states themselves, moving closer to conditions for the use of weapons of mass destruction, not at the beginning of a conflict as is often thought but after sustained violence.
The end of the “indispensable nation” is written in the rebalancing of the GDPs of major powers. The international system is unquestionably shifting toward a new model. But this could take two very different forms: either a more distributed and polycentric model, which political scientist Jean Baechler called the “oligopolar world,” or a new bipolar system centered around Washington and Beijing. The question remains whether, in the intermediary period, the world will be shielded from a breakdown of deterrence and conflict management, leading to a renewed episode of uncontrolled violence similar to that of 1914-1945.
A passive security policy, relying solely on nuclear arsenals and defensive alliances, is no longer sufficient to protect democracies. Therefore, it is necessary for them to contribute, through their reaffirmation, to the development of new regulatory mechanisms capable of keeping conflicts in check, preventing them from merging. This not only involves restoring shared norms on the use of force but also constructing a new security regime based on regional power balances that can function without depending on an increasingly erratic sole guarantor.
