Europe's security landscape has changed more rapidly over the past three years than at any time since the end of the Cold War. Russia's invasion of Ukraine forced governments across the continent to rethink long-held assumptions about deterrence, defence, and collective security. Few institutions have responded more dramatically than NATO, which has accelerated military planning, strengthened its eastern flank, and returned collective defence to the centre of its strategic agenda. Yet amid this transformation, one important question has received surprisingly little attention: can an alliance increase its own security without unintentionally making the wider security environment less stable?
Military history suggests that strengthening security is rarely as straightforward as increasing military capability. States often expand their armed forces because they believe doing so will prevent conflict. Their rivals, however, may interpret exactly the same actions as evidence of hostile intent. What begins as a defensive adjustment on one side can easily become a perceived threat on the other, encouraging further military expansion in response. Over time, both sides may become less secure despite investing heavily in their own defence.
This dynamic, commonly described by international relations scholars as the security dilemma, deserves far greater attention in today's debate about NATO's future. The Alliance's military adaptation after 2022 is understandable and, in many respects, unavoidable. The more difficult question is whether Europe can strengthen deterrence without creating a new cycle of long-term military competition. NATO's challenge is therefore no longer limited to responding to Russia's actions. It must also ensure that policies designed to preserve peace do not unintentionally make future confrontation more likely.
States rarely base their security policies on what their rivals say they intend to do; they respond to what they believe their rivals are capable of doing
The dilemma becomes clearer when NATO's recent policies are viewed through the eyes of its principal adversary. Since 2022, the Alliance has expanded its forward presence, approved new regional defence plans, increased the readiness of its forces, and welcomed Finland and Sweden into its ranks. For NATO members, these measures are defensive. They are intended to reduce the likelihood of future aggression by making any attack far more costly than it might otherwise be.
That interpretation, however, is not necessarily shared by Russia. Moscow has long argued that NATO's military expansion reinforces its own security concerns and justifies additional investments in military power. Whether one accepts that argument is ultimately beside the point. International politics is shaped not only by intentions but also by perceptions. States rarely base their security policies on what their rivals say they intend to do; they respond to what they believe their rivals are capable of doing. This is precisely why security dilemmas can persist even when neither side actively seeks war.
History offers several reminders of this dynamic. During the Cold War, both NATO and the Warsaw Pact portrayed their military buildups as defensive measures. Yet each interpreted the other's actions as evidence that even greater military preparedness was necessary. The result was decades of strategic competition that consumed enormous political and economic resources while repeatedly bringing Europe to the edge of dangerous crises. Today's security environment is different in many respects, but the underlying logic remains remarkably familiar.
Technology is making this security competition even more complex. During the Cold War, military balances were measured largely in terms of troop numbers, tanks, aircraft, and nuclear arsenals. Today, competition increasingly revolves around artificial intelligence, autonomous systems, cyber capabilities, space assets, and long-range precision weapons. These technologies undoubtedly strengthen military effectiveness, but they also introduce new uncertainties into crisis management.
One of the greatest risks is speed. Artificial intelligence can process information faster than any human decision-maker, cyber operations can unfold within seconds, and autonomous systems may compress the time available for political leaders to assess unfolding events. In a future crisis, the danger may not simply be deliberate escalation but miscalculation. The shorter the decision-making window becomes, the greater the possibility that misunderstandings or technical failures could produce consequences that neither side originally intended.
These developments do not diminish NATO's need to modernise. No responsible alliance can ignore technological change while potential adversaries continue to invest heavily in emerging military capabilities. Yet military innovation alone cannot provide lasting security. If technological competition advances faster than diplomatic communication and crisis-management mechanisms, Europe may enter an era in which deterrence grows stronger while strategic stability becomes increasingly fragile.
Beyond immediate military requirements, however, there is a broader question that deserves attention: what kind of security order is Europe seeking to build? Russia's invasion has understandably returned defence to the centre of European politics. Governments are increasing military budgets, expanding defence industries, and preparing for a period of sustained strategic competition. These decisions may be justified by the current security environment, but they also point to a future in which military rivalry risks becoming a permanent feature of European politics rather than an exceptional response to an extraordinary crisis.
The consequences of such a shift extend well beyond defence policy. Sustained military competition demands considerable financial resources, political attention, and industrial capacity. While security must remain a priority, governments must also balance these commitments against economic resilience, technological innovation, and broader societal needs. History demonstrates that prolonged geopolitical competition rarely affects military affairs alone; it gradually shapes political priorities, public expectations, and international relations for decades.
This is precisely why deterrence should not be viewed as a purely military concept. Throughout the Cold War, NATO's strength rested not only on military capabilities but also on diplomatic engagement, crisis communication, confidence-building measures, and arms control initiatives. Those mechanisms did not eliminate strategic rivalry, but they reduced the likelihood that rivalry would escalate into direct confrontation. In today's far more complex security environment, preserving channels of communication may be just as important as expanding military capabilities.
Recognising these risks does not mean questioning NATO's need to adapt. Russia's invasion of Ukraine demonstrated that credible deterrence remains essential for European security. An alliance that fails to modernise invites miscalculation just as surely as one that ignores emerging threats. The challenge, therefore, is not whether NATO should strengthen its deterrence posture, but how it can do so without reinforcing an open-ended cycle of military competition.
Ultimately, the debate is not about choosing between military strength and diplomacy. Durable security requires both. Military preparedness can discourage aggression, but lasting stability depends equally on political judgment, strategic restraint, and sustained dialogue. These elements should not be viewed as alternatives to deterrence; they are essential complements to it.
NATO has entered a new strategic era in which adaptation is both necessary and inevitable. Its greatest test, however, will not simply be measured by larger defence budgets, more advanced technologies, or stronger military capabilities. It will be measured by whether the Alliance can preserve credible deterrence while avoiding the unintended dynamics of a new security dilemma. History repeatedly shows that military power can prevent conflict, but lasting peace is far more likely when strength is matched by restraint, communication, and a shared commitment to reducing the risks of escalation.