Deterring ­Russia from Military Aggression Against Europe’s NATO Allies

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To deter Russia and shape a new security order in Europe’s own interests, European allies must now act with unified resolve and be prepared to carry the costs for their own security and defense. This is a tall order, since Russia currently doubts Europe’s resolve – ­especially in view of a fragile transatlantic relationship.

Since Russia’s full-scale invasion of Ukraine in February 2022 and the security policy U-turn in many European NATO countries, the German term “Zeitenwende” has come into international usage. Moreover, since the start of Donald Trump’s second term as president of the United States, with his wavering on US security commitments for NATO, the Atlantic Alliance has faced another Zeitenwende, this time with an urgent need for Europe to stand up to Russia in ways more credible than before.

Concerns about the US commitment to NATO, which is indispensable for the very functioning of deterrence, underscore the need for Europe to deter Russia from further aggression – something that will happen only when Moscow perceives Europe as having the necessary military resources and determination to use them. Russia will remain a military and political threat that must be countered by a credible NATO defense, and the US strategic shift toward reduced commitments in Europe and a stronger focus on the Asia-Pacific region is likely to prevail.

These two political shocks pose a number of dilemmas for the European pillar of NATO. At the heart is the issue of how to maintain credible political and military deterrence in the new security environment. Three questions stand at the forefront: How does Moscow perceive Europe’s current ability to counter Russian aggression? What European efforts are needed to build up sufficient conventional military forces, and what must be done to ensure the credibility of ­nuclear deterrence?

Europe’s Deterrence in the Eyes of Moscow

In war, it might play to your advantage if your opponent underestimates you; in deterrence, the opposite is true. Europe’s ability to deter will depend on how the aggressor perceives its posture. The European goal is to deter Russia from further aggression – something that will happen only when Moscow perceives ­Europe as having the necessary military resources and determination to use them. Currently, Russia seems unimpressed.

Even before 2022, Moscow found little use in talking to European countries and the EU. By 2020, Russia’s foreign policy position had already become one of growing frustration with, and even contempt for, ­European countries. In Russia’s strategic documents, Europe has been treated as a region that needs to shed its dependence on the United States. This is Russia’s way of signaling just how disillusioned it has become with Europe. Symptomatically, the Russian Ministry of Foreign Affairs renamed its Europe department in 2024 to the “Department for European Problems.”

Moscow will avoid a major military confrontation with NATO, especially while locked in war with Ukraine. It respects the military potential and economic resources at the West’s disposal. However, it also notes that Europe has been slow and even hesitant to engage its military industry at full throttle. Moscow also notes that none of the big European powers inside NATO are conducting major recruitment campaigns. Moscow’s most likely conclusion is that Europe is not setting up, training and exercising new units in the numbers needed with any kind of urgency.

Europe’s proposal to send a reassurance force to Ukraine did not impress Moscow. Russian Minister of Foreign Affairs Sergei Lavrov in July this year referred to the whole proposal as “fantasies,” while at the same time stating that Russia would never accept it. As it turned out, Europeans struggled to promise even 50,000 troops, reflecting the limited availability of land forces as well as political reluctance to take risks in confronting Russia. European countries also set preconditions: The US must contribute (albeit not by deploying troops to Ukraine), and a reassurance force would deploy only after a cease-fire. Such conditional and limited commitments do not deter Russia. They rather risk strengthening Moscow’s perception of European weakness: Europe will not have the military units needed for Ukraine’s security guarantees – nor will it be willing to commit them.

Russia is thus convinced that Europe not only lacks military power but is also weak in its resolve and willingness to sacrifice resources. In Moscow’s view, democracy makes Europe weak and unable to take decisions; when push comes to shove, Europe’s political leaders and citizens lack the capability and willingness to fight, pay the price, and stand united. Moreover, Russia believes Europe will fail to raise military spending due to its internal divisions and populations that have become used to comfortable lives and depraved by moral values inferior to those of Russia. A recurrent theme in Russia is also the country’s ability to sustain losses on the battlefield and the idea that this has created fear in Europe.

If Europe fails to replace US assistance, and if Europe leaves Ukraine to bleed economically and militarily, Moscow will consider its view of a weak Europe as vindicated

Overall, Russia’s view of Europe as weak undermines European deterrence and increases the risk of miscalculation. Despite signs that Europeans can act both in unison and resolutely when under pressure, ­Moscow remains more prone to note when the West is divided and Europe slow to act. Official statements and propaganda indicate that Russia still believes it is only a matter of time before Europe loses interest in Ukraine, especially without the US holding the effort together. Some of this bluster is probably propaganda, but on the whole, Russia acts in accordance with these assumptions about Europe’s trajectory of behavior. Negotiations on a possible settlement in Ukraine have so far only cemented Russia’s view of Europe as nothing more than a meddler thrown into the process too late and with little clout.

At the Moscow Victory Day Parade in May, Putin reiterated that “truth and justice” is on Russia’s side and expressed his pride in Russian bravery and resolve “that has always brought us victory.” This narrative is pervasive in Russia, as is the notion that not only history but also time is on its side.

Patriotic bluster aside, however, Moscow is aware that a united Europe that starts to build military power in earnest will become a problem for Russia. ­Longer-term, Russia knows its hand could be considerably weaker with a militarily stronger European component of NATO and a different presidential agenda in the White House. Its economy will not crumble, but it is suffering and falling even further behind in the global technology race.

Russia could therefore draw the conclusion that time is on its side mainly in the short term, and that there is a window of opportunity, a timeframe to act so it is not overtaken by history. Taking on the whole of ­NATO is not a palatable option for Moscow. However, if it can both undermine European unity and test ­NATO solidarity by challenging individual member states, Russia could edge closer to its goal of re-establishing and extending a sphere of interest in Europe.

Establishing Europe’s deterrence posture and making it convincing to Moscow is thus a pressing issue to solve now rather than later. Deterring Russia will require building a convincing European military power and showing an ability to respond in unison and quickly when Russia tests our resolve. It also means considering next steps and possible responses from Moscow before any escalation.

Russia is most effectively deterred in Ukraine. If ­Europe fails to replace US assistance, and if Europe leaves Ukraine to bleed economically and militarily, Moscow will consider its view of a weak Europe as vindicated. Europe’s support for Ukraine will thus be paramount for its ability to deter Russia.

NATO’s Conventional Capabilities

Uncertainty about the US commitment and the Trump administration’s intention to reduce its European defense contribution have prompted European NATO countries to increase their defense budgets. The push of the second Zeitenwende after Trump’s election has been stronger than that first brought on by Russian President Vladimir Putin’s full-scale invasion of Ukraine. The number of NATO allies spending more than 2% of GDP on defense is set to grow from 10 in 2023 to 31 in 2025. However, reaching the target of 3.5% of military spending (plus 1.5% on other defense-related costs), agreed at the Hague Summit, still requires a major effort from most allies.

Increased spending alone does not guarantee that Europe is acquiring enough of the right kind of capabilities. Four problems stand out. First, European deterrence is crippled by dependence on the US for certain critical capabilities and strategic enablers such as air defense systems, intelligence, surveillance, target acquisition and reconnaissance (ISTAR) capabilities, and deep strike capacity. Reducing the level of dependence requires long-term strategic investment.

Second, there is insufficient innovation and learning from Russia’s war against Ukraine, including drone warfare. Europe’s R&D investment in defense was EUR 11 billion in 2023, which is only a fraction of the USD 148.3 billion spent in the US. Europe has been slow to develop drone warfare capabilities, while Ukraine and Russia are competing on the speed of innovation for this type of warfare. Russia’s drone attack on Poland in September this year, as well as incidents with unidentified drones in Denmark and other countries, have exposed Europe’s unpreparedness. The EU responded with the European Drone Defence Initiative aimed at creating a multi-layered surveillance and defense system, which is an urgent priority along the EU’s eastern border and should eventually cover the whole Union.

Third, while the experience of Ukraine shows the critical importance of technological innovation, it also proves the need for conventional capabilities and manpower. Europe lacks sufficient military personnel for building the units and formations prepared to fight – and hence, deterring the adversary. For example, Germany has faced major difficulties in recruiting enough personnel to its armed forces, currently consisting of 181,000 troops, while Russia is estimated to have 1.1 million active-duty personnel and Ukraine roughly 880,000. The number of Russian recruitments is estimated to have been above 300,000 per year since 2022. Many European countries abolished conscription after the Cold War, but today all Nordic and Baltic countries (except for Iceland) have a mandatory military service, while some, including Germany, are discussing its reinstatement. The revival of conscription in Germany and other big European countries could be an important step not just for generating manpower but also for enhancing defense willingness in society and sending a signal to Russia about Europe’s preparedness.

Fourth, fragmentation of the European defense market reduces the efficiency of its rearmament efforts. For example, European countries operate 12 different types of main battle tanks, while the US uses just one. The EU has instruments to reduce fragmentation by encouraging joint procurement and multinational projects, especially for strategic enablers, but has not yet effectively implemented them.

There are signs that the Europeans can get their act together. Europe has stepped up its support of Ukraine since the Trump administration began phasing out US aid. Following the Trump-Putin summit in Anchorage in August 2025, European leaders mobilized for a diplomatic effort to persuade the US not to pressure Ukraine to make major concessions to Russia. At the same time, the discussion on deploying European assurance forces to Ukraine as part of security guarantees has again signaled Europe’s limited resources and, perhaps even more importantly, its hesitation and lack of resolve. As noted above, the European plan to send a limited number of troops to Ukraine after a ceasefire has not deterred Russia from continuing the war. It is more difficult to assess what this actually tells us about NATO’s deterrence capability. One reason for the offer of limited deployments to Ukraine is that European NATO countries prioritize their commitments within the alliance.

All the shortcomings outlined above underscore Europe’s continued dependence on the US for its defense and the need for diplomatic efforts to keep the US engaged. The direction is clear, however: Europe is working on reducing its dependence and building up deterrence capability of its own. No doubt Russia is watching this process closely and is trying to slow Europe’s rearmament through hybrid methods of influence such as fueling domestic cleavages, magnifying political views within Europe that are favorable to Russia’s interests, and conducting sabotage operations.

Nuclear Deterrence After the Second Zeitenwende

Put simply, a credible nuclear deterrent consists of three components: first, nuclear weapons and their delivery systems; second, a willingness to use them in an emergency in a way that is recognizable to the adversary; and third, a strategy for how and when such weapons should be used. Such a strategy is particularly important in an alliance such as NATO, which consists of nuclear and non-nuclear states and in which the nuclear powers have made a nuclear commitment to their allies.

During the Cold War, NATO had all three elements: a broad spectrum of nuclear weapons in Europe, credible extended deterrence from the US, and a nuclear strategy supported by all NATO members – both nuclear and non-nuclear.

After the end of the East-West conflict and in the belief in a partnership with Russia, NATO’s nuclear posture was reduced to a minimum, and the strategy, with its plans and rules of engagement, was abolished. Only the US nuclear commitment remained intact and has been repeatedly reaffirmed by every US president since 1989. With the second Zeitenwende, sparked by Donald Trump’s second term in the White House, even the American commitment to its European allies is now in question and nuclear deterrence has been weakened overall.

The nuclear discussion in NATO that has arisen in the wake of Russia’s attack on Ukraine has so far focused on two of the three dimensions mentioned above, namely on the nuclear posture and its potential modernization and second on what would happen if Washington closed the nuclear umbrella over Europe. In both areas the debate has advanced in recent years.

The third crucial question though, namely that of a nuclear strategy, has so far been largely ignored. What political and military principles should apply to the possible use of nuclear weapons by NATO, what targets would be eligible for such use, and what procedures should apply to the approval of such an extreme case within the alliance? If NATO wants to increase the credibility of its nuclear deterrence vis-à-vis Russia, it will have to take on the cumbersome and controversial process of strategy development.

If NATO wants to increase the credibility of its nuclear deterrence vis-à-vis Russia, it will have to take on the cumbersome and controversial process of strategy development

Fortunately, NATO does not have to reinvent the wheel but can resort to elements of the Cold-War nuclear strategy – provided it carefully considers the new security environment. This former strategy also consisted of three core elements. First, the “General Political Guidelines” (GPGs) for the employment of nuclear weapons in the defense of NATO represented a NATO consensus on the political conditions under which a first or follow-on use of nuclear weapons could be contemplated. Second, it contained rules and regulations on consultations among NATO allies prior to a nuclear employment. The third element consisted of annual targeting conferences to evolve a consensus on where nuclear weapons should be employed and on whether the purpose of nuclear weapons would be a military or a political one to persuade the attacker to back down.

While these three elements of NATO’s nuclear strategy evolved under the conditions of the East-West conflict, the circumstances today are largely different. Although Russia has once again become a military and political threat to NATO, it is no longer – as the Soviet Union once was – vastly militarily superior to NATO in Europe. Moreover, Moscow has lost its former alliance system, the Warsaw Pact. This means that rapid, expansive military advances by Russia from east to west, with which the Soviet Union once sought to reach the Atlantic in a matter of weeks before comprehensive American reinforcements could reach Europe, are no longer to be expected. Regarding NATO’s nuclear deterrent, American nuclear strikes on NATO territory, as once anticipated against advancing Soviet forces, are hardly imaginable today. Nor is it necessary to make quick decisions about nuclear escalation before the attacker can create a fait accompli.

Putting the experiences of NATO’s nuclear strategic evolution in the Cold War into the context of today’s security challenges in Europe reveals at least five insights for the development of a NATO nuclear strategy that will boost the overall credibility of the Alliance’s deterrence.

First, this strategy must be directed primarily against Russia. Regardless of China’s rise in power politics on the world stage, a direct attack by China on NATO is highly unlikely. China plays at most an indirect role, because the US, as a global power, must deter both Russia and China and, in the event of a military crisis in the Indo-Pacific, could relocate nuclear weapons from Europe to this region. This, in turn, could influence NATO’s nuclear planning for Europe.

Second, a nuclear escalation by NATO would first and foremost serve the political goal of demonstrating a willingness to defend itself against the attacker and persuading it to cease hostilities. Cold War concepts of nuclear warfighting are no longer imaginable.

Third, NATO’s nuclear consultation mechanisms developed in the past could essentially be retained. Although France is not represented in NATO’s Nuclear Planning Group (NPG), it should be included in such processes. However, the ultimate decision-making authority still lies solely with NATO’s nuclear powers. Majority decisions or vetoes by individual member states remain inconceivable.

Fourth, the procedures laid down in a future nuclear strategy must be practiced regularly in appropriate exercises. In the past, there were biennial WINTEX (Winter Exercise) drills, in which civil-military coordination in the event of a crisis and the political procedures relating to the use of nuclear weapons were rehearsed. These were discontinued at the end of the 1980s and should be reintroduced in an adapted form.

Finally, the necessity of nuclear deterrence and the associated strategies and concepts must be communicated openly. This would not only send a signal of resolve to Russia but would also support public approval for the delicate concept of nuclear deterrence.

Conclusion and Recommendations

As the security situation in Europe continues to deteriorate, NATO’s European pillar stands before a tall order in deterring Russia. Moscow sees Europe as weak and anticipates an opportunity in the prospect of weakening US presence. It is watching closely what measures European allies take to build both conventional and nuclear military deterrence.

Considering Russia’s perception as well as NATO’s conventional shortcomings and nuclear-strategic requirements, seven recommendations need to be taken into account to strengthen NATO’s overall deterrence against the military and political threats posed by Russia.

1. “Europe” in Russian thinking is both the EU and NATO. The EU and NATO must agree on strategic signaling and anchor this among the countries expected to contribute to and participate in, for example, convincing security arrangements for Ukraine. Establishing mechanisms for such consultations among an inner core of European countries that are willing to contribute to deterring Russia will both improve coordination and exclude countries that hinder effective deterrence.
2. Europe needs to understand Russia’s perception of European deterrence measures. This calls for dedicated, systematic, and long-term analysis of Russian decision-making, security thinking, and possible responses. Such analysis must, moreover, be both policy-relevant and also independent from policy processes, in order to avoid political wish lists influencing the research process.
3. European countries need to carefully analyze the lessons from the war in Ukraine when strengthening their defense. European NATO countries, working in close cooperation with Ukraine, have to invest much more in defense technological innovation, including drones and anti-drone systems, but also in conventional capabilities and manpower.
4. The revival of conscription in Germany and other large European countries would send a strong signal about Europe’s enhanced preparedness and the understanding that we are in it for the long haul.
5. Dependence on the US should be gradually reduced, especially with regard to strategic enablers and critical capabilities such as air defense systems, as well as intelligence, surveillance, target acquisition and reconnaissance (ISTAR) capabilities, and deep strike capacity.
6. NATO must start developing a contemporary nuclear strategy that draws on parts of the nuclear consensus developed in the Cold War. However, these former nuclear guidelines must be adapted to the current and future strategic environment. This would include a political understanding of the use of nuclear weapons, a realistic nuclear targeting, and meaningful nuclear consultations.
7. The procedures and guidelines in the new nuclear strategy must be practiced regularly in appropriate exercises along the lines of the biennial WINTEX (Winter Exercise) drill, which combined military and political elements of a nuclear crisis. These were discontinued at the end of the 1980s and should be reintroduced in an adapted form.

European Zeitenwende Strategy Group

This paper is part of a series of publications prepared in the framework of DGAP’s “European Zeitenwende” Strategy Group, which seeks to help reconceptualize European security in a rapidly changing geopolitical environment. Against the background of Russia’s ongoing war of aggression against Ukraine, a strained transatlantic relationship, growing rivalry with China, and changing global and regional orders, Europe needs to strategically reposition itself if it wants actively shape security on the continent.

Europe’s strategic reorientation should be inspired by those who – as direct neighbors to Russia and Ukraine – best understand the urgency to act. The Strategy Group therefore draws on in-depth analytical discussions with experts and stakeholders from Central, Eastern, and Southeastern Europe, as well as the Nordic and Baltic states, where debates on security are arguably most advanced, to propel a “Zeitenwende” of security policy and thinking in Europe.

Chaired by the German Council on Foreign Relations, the group met regularly online and in-person over the course of 2025. Convinced of the need for a comprehensive approach, it considered different dimensions of resilience, including security and defense, economic security, institutional reform, and societal cohesion.

The present paper series represents the results of the group’s analysis. It seeks to address questions and challenges that in the currently evolving security discourse remain conceptually and practically underdeveloped. By providing concrete analysis, definitions, and reflections to these open questions, the series aspires to add substance to the European Zeitenwende debate on security and defense. The ultimate question of all the papers is how to strengthen European agency in providing European security and in ensuring peace and stability in a new geopolitical context.

Members: Robin Allers (Norwegian Institute for Defence Studies), Hiski Haukkala (Finnish Institute of International Affairs), Wilfried Jilge (German Council on Foreign Relations), Karl-Heinz Kamp (German Council on Foreign Relations), Pavlo Klimkin (Center for National Resilience and Development), Jana Kobzova (European Council on Foreign Relations), Nicole Koenig (Munich Security Conference), Stefan Meister (German Council on Foreign Relations), Carolina Vendil Pallin (Swedish Defence Research Agency), Katri Pynnöniemi (University of Helsinki & Finnish National Defence University), András Rácz (German Council on Foreign Relations), Kristi Raik (International Centre for Defense and Security), Toms Rostoks (National Defence Academy Latvia), George Scutaru (New Strategy Center), Margarita Šešelgytė (Vilnius University, Institute of International Relations & Political Science), Marcin Terlikowski (Polish Institute of International Affairs)

The European Zeitenwende Strategy Group was established in the format of the project “In Together – Shaping a Common European Future,” which is funded by Stiftung Mercator.

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