Since 1945 and the first use of nuclear explosives, a conviction has structured Western strategic thinking: the existence of these “absolute weapons” makes any war of conquest between major powers unthinkable, making the territory of nuclear-armed states inviolable. As a result, these states could only face each other indirectly, in limited wars, the intensity of which would never reach the hyperbolic violence of the first two world wars.
However, this certainty has been undermined. By invading Ukraine, a country whose independence and security it had guaranteed under the Budapest Memorandum in 1994, Russia used its nuclear arsenal as a shield (without risking direct involvement of the United States) to conduct a conventional war of conquest. This Russian invasion caused a profound disruption of deterrence mechanisms, the consequences of which may not have been fully diagnosed.
The extent of what is possible under the “nuclear umbrella,” without triggering a collapse, has significantly increased. The war in Ukraine demonstrated that a high-intensity conventional confrontation, pursuing explicit territorial annexation goals, could unfold without the nuclear threat being activated, neither by the aggressor to protect its gains nor by the states supporting Ukrainian defense to end it.
The concept of a nuclear “threshold,” theorized in 1960, assumed a precise line beyond which atomic warfare became certain. Since the beginning of the war in Ukraine, this notion can no longer be strictly understood. In reality, behaviors follow more complex mechanisms: there is an uncertainty zone, an intermediate space where an infinite number of hostile acts remain possible without automatically leading to ultimate escalation.
In other words, there is an increase in the threshold at which the behavior of certain actors becomes intolerable. And it is precisely this elevation that opens a window of opportunity for “revisionist” powers, wanting to modify the system rules to their advantage.
For example, by using force to annex new provinces and 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 of their delineation can only be made within existing internal administrative boundaries. This principle has been applied in decolonizations and the end of the USSR, with few exceptions in seventy years (Tibet acquired by China in 1950, Kashmir, the border between the two Koreas, Israeli-Arab wars, Northern Cyprus).
The return of wars of conquest
We see here the most serious risk: not a “Third World War” deliberately declared by a power or group of powers, resulting in total nuclear war, but a multiplication of simultaneous conventional conflicts exhausting American capacities and will that could be called a “world war below the threshold” (i.e., not causing nuclear weapon use initially).
For the past five years, the most significant ruptures have been caused by nuclear powers themselves. Russia attempted to subjugate Ukraine through a blitz offensive and formally annexed five provinces before engaging in a protracted war with lasting consequences for the European order. Israel, a non-declared nuclear power, responded to Hamas’ attack on October 7, 2023, with unprecedented military operations in the Gaza Strip, Lebanon, Syria, against Houthi rebels in Yemen, and finally against Iran, following its doctrine of “disproportionate response.”
Moreover, the United States, far from being mere observers of the system’s deregulation, have become one of its agents. The operation in Iran was launched without UN mandate or consultation with the US Congress. Washington openly threatens NATO members, thus undermining the institutions that the US had themselves contributed to building. The guarantor of the previous order, tired of financing the Alliance, initiated a brutal reform that disrupts its structure and threatens to destabilize it.
Other conflicts, while not involving nuclear arsenals, have been initiated 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 (Nagorno-Karabakh) and the exile of over 100,000 Armenians, without international intervention.
To this conflict are added wars between Cambodia and Thailand, India and Pakistan, or Pakistan and Afghanistan. These situations demonstrate that the resurgence of limited local wars was not an accident but a significant trend, adding to the insurgent struggles of previous decades.
While not all of these wars have led to significant border changes, neither the United States nor its strategic competitors are able to regulate them all at once. The US could once balance all regions and tensions through external intervention (traditionally called “offshore balancing”), but the proliferation of emergencies and conflicts no longer allows for sufficient action on an equal budget. The multiplication of conflicts shows that this has become much more challenging. This leaves much greater scope for local actors to alter their relationships with their neighbors.
In particular, Russia has shown other revisionist powers that economic sanctions can be absorbed, that Western war efforts have industrial and political limits, and that nuclear protection offers a wider range of conventional action than previously thought. All of this constitutes an “incentive,” in the precise sense given by game theory (an increase in reward for an action or a reduction of risk), to use force to reshape territory and power balances. This could even call into question the nature of the international system.
When conflicts threaten to merge
Raymond Aron, in the book “Les Guerres en chaîne” published in 1951, noted that American strategists of the immediate post-war period only considered two scenarios: armed peace without direct confrontation or total war triggered by nuclear attack. According to him, they overlooked a third scenario, that of “limited hot wars,” like the Korean War (1950-1953), which took America by surprise.
However, despite the sometimes terrible losses they caused, none of these “hot wars” escalated into a conflict involving two coalitions directly intervening. External interventions, such as those of the Soviet Union and China in favor of North Vietnam, had to be discreet, or restricted to defensive aid to protect the ally’s borders.
The nuclear deterrence had thus far confined local wars to the territories of the states involved. But the multiple, intense, and distributed conflicts we are witnessing without being able to stop them have now taken on such magnitude that the possibility of a chain…
[NOTE: The article continues with further analysis and discussion on the topic in the original text]
