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The 1964 noir-classic Dr. Strangelove describes the cornerstone of alliances – bound together, an adversary must carefully consider attacking. NATO as an international organization boasts a military force over one-million strong. The Alliance has demonstrated the ability to deploy coordinated, lethal force anywhere in the world. NATO warned Russia that there will be consequences for attacking their partner, Ukraine. In January 2022, Russia still attacked. Why? Did NATO and the U.S. fail to properly implement a strategy of deterrence? Did Russia in fact deter NATO as it used brute force to impose their will on their neighbor? Does this mean extended deterrence is dead? With Russia’s expected three-day action entering its second year, what can the world observe of deterrence?

Deterrence is the art of producing in the mind of the enemy…. the fear to attack (Dr. Strangelove, 1964).

Examining the Russo-Ukraine war through the lens of deterrence theory provides a framework to assess a cornerstone of U.S. and NATO strategy for the past 75 years in practice. As the international community exits a unipolar environment and resumes great power competition, the war validates requirements to effectively implement a deterrence strategy, demonstrate its effectiveness, and increase its future effectiveness. Close examination demonstrates deterrence is effective and extended deterrence, while ineffective in Ukraine, can be effective through increasing partner resilience.


What is Deterrence?

In practice, deterrence takes two forms: punishment and denial.[1] In deterrence by punishment, the protagonist threatens military force to punish an antagonist if it takes a specific action; if the antagonist does not act, the protagonist does not punish. In deterrence by denial, a protagonist threatens to use military force to keep an antagonist from achieving their desired outcomes or to make it so expensive it isn’t worth trying. Again, if there is no action by the antagonist, the protagonist does not use force.

NATO policy provides two examples of this. NATO maintains nuclear weapons as a cornerstone of defense – an attack on the core interest of Allies’ sovereignty could result in a nuclear response.[2] This threat of overwhelming response to punish aggression and ambiguity on thresholds for crossing from the conventional to nuclear layer deters aggression against the Alliance. NATO also maintains over 40,000 troops in a high-readiness level, prepared to respond within 15 days of activation. This force could block aggression against the Alliance and keep an aggressor from ever meeting the goals of their military offensive. In both these examples, NATO seeks to change the cost-benefit calculation of aggressors.

NATO also maintains over 40,000 troops in a high-readiness level, prepared to respond within 15 days of activation. This force could block aggression against the Alliance and keep an aggressor from ever meeting the goals of their military offensive. In both these examples, NATO seeks to change the cost-benefit calculation of aggressors.

According to Deterrence Theory, threats of punishment and denial alone are insufficient to impact an aggressor’s cost-benefit calculation. To be effective, the protagonist’s threat must be capable, credible, and effectively communicated.[3]The antagonist must believe the protagonist has the capability to impose the threat – does the state have the power to carry out the threat? The antagonist must believe the protagonist will use the threat – does the state have the will to commit the blood and treasure to carry out the threat? Finally, the antagonist must understand the threat – does the state effectively communicate the cost to an aggressor for taking an action and the cost avoidance if it doesn’t? Without these three components, a threat will not adjust the aggressor’s calculations or deter an action.

Implementing the three components have separate challenges. Capability is the most straight forward – an assessment of NATO’s capacity to take military action across the air, cyber, land, sea, and space domains compared to Russia’s ability to defend in these domains indicates capability. Credibility is less mathematical as it assesses if the 30 members of NATO can agree to unified military action. Can one member carry the Alliance forward or does the Alliance have to pull a member(s) along? What does history and the current political environment suggest? Finally, communication can offer the biggest challenge – communicating across cultures the consequences of action, the assurance of no threat for inaction, opportunities to avert conflict, and the capability and credibility to use force if Russia acts must take different forms. Public statements, diplomacy, and military mobilization are forms of communication that must be clearly understood to be effective. If the protagonist and antagonist do not have similar understandings of the capability, credibility, and communication, deterrence will not be effective.[4]

The modern environment continues to make deterrence more complex to successfully implement as a strategy. For instance, an actor (or group of actors) can offer extended deterrence, where the protagonist offers a threat to an antagonist to deter actions against a protégé. Generally associated with a nuclear threat, extended deterrence usually has an elevated challenge with credibility as the protagonist must convince the antagonist it would go to war for the protégé.[5] The intervening protagonist has many levers to deter action, including reassuring the protégé of its protection against the antagonist, accommodating the antagonist to promote a level of peace, restraining the protégé’s threats, or using deterrent threats to stop to antagonist.[6] Ukraine’s innovative use of technology and potential targeting inside Russia demonstrate that in extended deterrence, the protégé’s actions can be as impactful as the protagonist’s or antagonist’s actions. Even prior to the 2014 invasion of Ukraine, NATO has tried to bolster the effectiveness of extended deterrence, through deterrence by resilience.

Similar to Schelling’s “deterrent defense”, NATO’s deterrence by resilience relies on states (both Allies and partners) hardening their ability to resist offensive action to ultimately deny the aggressor’s objectives or allow NATO time to mobilize a response to deny or punish the aggressor.[7],[8],[9] By 2022, NATO established the new Resilience Committee observing “[r]esilience is both a national responsibility and a collective commitment”.[10] While the Committee sets priorities and the requirements change, maintains baseline requirements, including continuity of government services, energy supply resiliency, displaced personnel management, food and water security, and communications network resiliency.[11]


NATO, Russia, and Ukraine

Before examining Russia’s decision to invade Ukraine it is important to understand fundamentals of NATO. Founded in 1949, the Alliance’s founding document, the North Atlantic Treaty, outlines NATO’s enduring purpose, which is to achieve collective defense for preserving peace and security.[12] NATO’s core interest is safeguarding members’ sovereignty through deterrence and collective response. NATO maintains a strong interest in the security and stability of its neighbors. The founding Treaty is specific that the defensive agreement protects Treaty Allies and that to enjoy those protections, a state must join the Alliance.      

NATO, Russia, and Ukraine have been tied together since 1994 when Ukraine – heirs of the world’s third largest nuclear arsenal – signed the Budapest Memorandum. Ukraine pledged to end its nuclear weapons program and transfer all Highly Enriched Uranium to Russia through this document, also signed by Russia, the United Kingdom, and the United States. In exchange, signatories affirmed – not guaranteed – to “respect the independence and sovereignty and existing borders of Ukraine” and to “refrain from the threat or use of force” against that country.[13],[14],[15] A decade later in 2008, Ukraine demonstrated intention for even greater partnership with NATO as they became a contributing nation to the NATO-led International Security Assistance Force.[16] The same year, NATO re-affirmed its commitment to states’ right to self-determination of alliances and started the Annual National Programme (ANP) for Ukraine, publicly recognizing that Ukraine would become a NATO member.[17]

Ukraine’s goals of joining NATO directly clashed with Russia’s sense of security. As early as 1990, when NATO sought to bring a unified Germany into the Alliance, Russia sought concessions that NATO would not expand further west.[18]In February 2014, following the Revolution of Dignity, Russia disregarded its commitment to respect Ukrainian sovereignty and seized the Crimean Peninsula, which increased Ukrainian resolve to join NATO.[19] After 2014, NATO and individual NATO members sought to build Ukrainian capacity in key areas across 13 support measures including Capacity and Institution Building, Logistics and Standardization, Cyber Defense, and Medical Rehabilitation.[20]

Continuing to progress membership, President Zelenskyy approved Ukraine's new National Security Strategy in 2019, outlining an enhanced partnership with NATO to work toward membership.[21] NATO publicly supported Ukraine’s goal of membership and lauded Ukraine’s progress in annual ANP reporting. By December 2021, Russia’s concern with NATO expansion into Ukraine came to a head as troops massed on the Ukraine border. President Putin demanded formal agreements from NATO that Ukraine would not be able to join NATO, stating “the ball is in their court… they must answer us something."[22]


Analyzing the Deterrent Threats

In deterrence, initiative belongs to the antagonist, who chooses whether and when to attack. With Ukraine still a partner, not a NATO member, there were still several deterrent threats that Russia likely considered when deciding to act. Tools to evaluate Russian assessments are limited but comparing conditions in 2014 to 2022 is useful. 



In 2022 as in 2014, NATO’s conventional and nuclear capacity were unrivaled in the world. Drawing on the resources of 30 countries, NATO possessed the military capability to both punish and deny objectives. NATO does have limitations. In 2013, the U.S. redeployed its last forward stationed armored unit from Europe. The deployment of an armored battalion set in 2014 allowed for combined arms training but signaled that the U.S. military, a significant contributor of combat forces, would not immediately contribute significant combat force to a NATO response.[23] NATO also substantially relies on the U.S. nuclear umbrella. Doubts about the U.S. willingness to engage in nuclear war over Europe and the lack of tactical nuclear weapons on the continent could drive NATO to a conventional response to a nuclear event. These two shortfalls in capability could be opportunities for Russia.

When Russia seized Crimea in 2014, Ukraine had significant challenges responding. Without any formal defensive agreements with other nations, Ukraine’s armed forces were the only available response. Outnumbering the Ukrainian army by more than four to one, Russia had a significant overmatch in equipment and personnel. At the same time, a combination of laws prohibiting use of the army, political corruption, and lack of trust between the people and the government significantly hindered the Ukrainian response to Russian aggression.[24]  

In the seven years after Russia commenced its attack on Ukraine, the Ukrainian armed forces progressed with NATO assistance.  Leader training, combat training and support missions with ISAF developed resilience in the armed forces. NATO’s 2019 assessment found Ukraine’s armed forces had progressed from a 150,000-strong force that could only muster one brigade capable of combat operations to a capable 250,000-strong force, many of whom had benefitted from NATO training missions and with limited numbers of advanced NATO weapons. Under President Zelenskyy, Ukraine also reduced corruption, with NATO estimating that corruption reforms in between 2016 and 2018 saved the country $2 billion.[25]

Russia likely considered its own military strengths when weighing advances in Ukrainian capability. Beginning in 2008, the “New Look” reforms transitioned the Russian Army from a 5-million-man force based on conscription, to a leaner force balancing conscription and professional soldiers in a brigade structure.[26] The 2014 occupation of Ukraine, subsequent engagements, and operational deployments to Syria confirmed the efficacy of these modernizations to Russian officials. Operations in Syria also enabled Russia to trial integrating private armies such as the Wagner Group. 



Ahead of Russia’s illegal annexation of Crimea in May 2014, NATO had many competing claims for its attention, from the Arab Spring movement, the Eurozone crisis, and the disruption to intelligence sharing in the wake of the Snowden leaks. Against this backdrop of domestic and international turmoil, NATO did not respond militarily to the fait accompli of a partner nation’s territory being annexed, merely using sanctions to attempt to coerce Russia to withdraw.

Ahead of the 2022 attack on Ukraine, NATO countries were even more internally focused, due to COVID and containment measures, market disruptions, and Brexit. The U.S. evacuation from Afghanistan in August of 2021 caught international and local headlines as the U.S. ended a 17-year occupation, causing a mass refugee migration out of Afghanistan. The U.S. also expended trillions of dollars to mitigate the impacts of COVID and started to see significant inflation from a demand-driven market.

Considering the two time periods, Russia could estimate an attack on a NATO partner in early 2022 would not bring a military response from NATO. Despite closer ties with Ukraine for training, NATO was still not committed to a military response to Russian aggression in Ukraine. Russia likely understood that an attack on a NATO ally would result in punishment and denial, but an assault on a non-ally would not result in a military retaliation. 



The most observable communication of threat is the movement of forces. Following the Russian annexation in 2014, NATO communicated two messages. At the Wales Summit of 2014 NATO agreed to deploy a rotational multinational force to Baltic allies and Poland.[27],[28] In the same summit, NATO further committed to work with their Partner of Distinction, Ukraine, with a mission “designed to enhance Ukraine's ability to provide for its own security” through “substantial new programmes with a focus on command, control and communications, logistics and standardisation, cyber defence, military career transition, and strategic communications.”[29],[30] Agreements resulted in rotational battalions in Baltic states and Poland and NATO members (primarily the U.S) investing over $4 billion in Ukrainian resilience.[31]The clear message was that NATO reserves military presence for allies but will assist partners to develop resilience to deny Russian victory.

In the buildup to Russia’s 2022 invasion, NATO reinforced these messages. The Brussels Summit in June 2021 highlighted the Alliance’s preparedness for mutual defense if Russia attacked a NATO state. The conference also highlighted that “resilience is essential for credible deterrence and defence” and that NATO would help partners enhance their resilience.[32] Consistent with messaging of other NATO Allies, the U.S. made it clear the U.S. would not deploy troops to defend Ukraine.[33]  At the same time, President Zelensky met with NATO Secretary General Jens Stoltenberg seeking security commitments to help deter a renewed Russian invasion predicted weeks away. Consistent with earlier engagements, the Secretary General committed to Ukraine’s future path to join the Alliance and severe economic punishment for Russia if it attacked, but not military support.[34]


When to Act?

For Russia to decide to attack, the perceived benefit for the action would need to exceed the risk from the deterrent threats. Since the fall of the Soviet Union, Russia has viewed NATO expansion and “Westernization” of border states as a significant security threat. An attack on a NATO ally would almost certainly result in significant military, political, and economic punishment and likely denial of any military objectives – NATO clearly communicated this, had the capacity to enforce, and credibility would act. Further military action in Ukraine could finally halt eastward expansion of NATO and European Union membership and reestablish overwhelming influence in Ukraine. The benefits of this action must overcome two threats – a NATO threat of extended deterrence through punishment and a Ukrainian threat to deny military and political objectives. 

NATO clearly stated that there was no threat of military response with the statements came both from President Biden and NATO Secretary General Jens Stoltenberg. They clearly stated that there would be no military response for Russian action.[35],[36],[37] Ukraine’s threat of denial was equally ineffective. In 2014 Ukraine could only muster 6,000 troops to conduct operations at that rate of readiness. NATO training and member equipment would improve the performance of Ukraine, but Russia could overcome the limited weapon systems through their superiority in mass numbers. It also perceived that if the Ukrainian military stood to fight, the government would likely flee. These shortfalls in both deterrent threats would not outweigh potential benefits for Russia. 


Observations and Implications

1) Denial by Resilience can work. Since 2014 and the rise of Russian aggression in Europe, NATO has focused on national resilience for both allies and partners. Ukraine’s ability to survive the initial invasion with adequate government, military, and civil systems in place provided an opportunity for the international community to support the country. This is particularly critical as NATO’s Strategic Concept maintains minimal forces in a “very high ready” state, with the bulk of forces planned to reinforce within 14-30 days. This observation also adds credibility to the threat of deterrence by resilience (denial), requiring a state to analyze the fragility of an opposing state before taking military action.

2) The International Community can reinforce resilience without nuclear escalation. Experience in Ukraine demonstrates NATO can help build and reinforce a partner nation’s capability to fight without decisive engagement. This is demonstrated through the effectiveness of the Comprehensive Assistance Package (CAP) in building capacity and the ability to reinforce Ukraine’s materiel requirements. NATO can provide conventional support to Ukraine without a nuclear response from Russia. This increases the capacity and credibility of the partner’s threat of denial. Looked at in another way, this capability provides NATO a means to extend the deterrent umbrella and not rely on coercive threats to support partners.

3) Signaling nuclear escalation remains an effective deterrent against NATO. Since the beginning of the 2022 offensive, Russia has leveraged their Strategic Deterrence concept to threaten nuclear retaliation to deter support for Ukraine. In addition to using energy as a weapon for blackmail, Russia has suggested that NATO intervention could escalate the conflict from the conventional to nuclear layer. To add credibility and further communicate this, Russia announced in October 2022 that the “annexed” states were integrated parts of Russia and that efforts to retake them were attacks on Russia core interests.[38] Faced with a capable, communicated threat with some credibility, Russia’s threat is a likely cause of NATO’s choice to has limit the range and effectiveness of systems provided to Ukraine. 

Russia has also demonstrated that credibility is perishable. Despite threats, NATO has trained and supplied Ukraine troops since the beginning of the conflict without a response. China and India have both publicly stated that the use of nuclear weapons is unacceptable. As trading partners and economic lifelines around NATO-led sanctions, Russia is very unlikely to defy these powers. As inaction and international disapproval erode credibility, deterrence plays less in NATO’s decision as demonstrated through supplying more advanced, longer-range systems to Ukraine. 

Despite threats, NATO has trained and supplied Ukraine troops since the beginning of the conflict without a response.

This situation increases the risk of escalation. As the situation develops, NATO must continue to assess Russian communication and evaluate the credibility of the Russian threat to avoid overlooking a redline that might lead Russia to use nuclear weapons.

4) NATO’s Credibility in extended deterrence remains a vulnerability that jeopardizes aspiring nations. Structured as a defensive treaty, NATO remains challenged to extend the deterrence umbrella. The 2022 Strategic Concept demonstrates NATO’s commitment to defense, highlighting that all the three core missions are to “ensure collective defence and security of all Allies”.[39]  NATO has recently demonstrated at least three options to help assure partners and deter aggressors in this vulnerable period. The most promising is expedited membership, demonstrated by efforts to fast-track membership for Sweden and Finland. Unfortunately, NATO has demonstrated that the fast track for concurrence from 30 sovereign states isn’t fast. Another option would be tripwire forces, such as the Enhanced Forward Presence (EFP) troops deployed to the Baltic states. This option assures the allies and partners of NATO’s intentions, while causing a deterrent dilemma for an aggressor state of attacking member forces. The third option is increasing resilience of the aspiring member as demonstrated in Ukraine. As Ukraine met conditions for the CAP, it increased the resilience of the entire government, including military and civilian response forces. NATO members also contributed billions of dollars to improve military capability. The investment in an aspiring partner did not prove effective in deterring Russian aggression, but it did prove effective in realizing denial of Russian victory. Of the three options to mitigate the risk to aspiring partners, only NATO members’ investment in resiliency proves effective in bolstering capability of a deterrent threat.


Concluding Remarks

The Russo-Ukraine War demonstrates the limits of extended deterrence and the vulnerability of aspiring states seeking admission into NATO. NATO’s core interest as a defensive alliance remains protected. Escalation from conventional to nuclear weapons remains deterred as of May 2023. From the Russian perspective, NATO has not directly intervened on Ukraine’s behalf and has not supplied weapons that would alter the strategic environment against Russia. In these three instances, threat's capability, capacity, and communication exceed the potential benefit of action. Where deterrence did fail to alter Russia’s aggression, the war has demonstrated that NATO can effectively reinforce a state’s resilience to enable deterrence by denial. The war also verifies Shelling’s theory that deterrence can effectively stop escalation between levels of weapons from conventional to nuclear. A major implication for NATO policy is that extended deterrence for non-member states requires costlier signaling than can be provided by money and training alone, and that when extended deterrence fails, the money and training required to impose high costs on an aggressor are significantly higher.


[1] Thomas C. Schelling, Arms and Influence (S.L.: Yale University Press, 1966): 69-73

[2] NATO, “STRATEGIC CONCEPT Adopted by Heads of State and Government at the NATO Summit in Madrid.” 22 June 2022, 7-8.

[3] T.V. Paul, Patrick M. Morgan, and James J. Wirtz, Complex Deterrence: Strategy in the Global Age. (Chicago: University of Chicago Press.Paul, 2009): 3.

[4] Tami D. Biddle, “Coercion Theory: A Basic Introduction for Practitioners,” Texas National Security Review, Vol. 3 (Spring 2020): 97.

[5] Paul, Complex Deterrence, 279-282.

[6] Paul, Complex Deterrence, 289-292.

[7] Schelling, Arms and Influence, 78.

[8] NATO, Strategic Concept, 9-11. 

[9] Jamie Shea, “NATO Review - Resilience: A Core Element of Collective Defence.” NATO Review. 30 March 2016.

[10] NATO, “Resilience Committee.” 7 October 2022.

[11] Shea, “NATO Review.” 

[12] NATO. 1949. “The North Atlantic Treaty.” NATO. 4 April 1949.

[13] Steven Pifer, “The Budapest Memorandum and U.S. Obligations.” Brookings, 4 December 2014.

[15] Aaron Blake, “Analysis | What the Budapest Memorandum Means for the U.S. on Ukraine,” Washington Post, 1 February 2022.

[16] “ISAF Regional Commands & PRT Locations Herat Qala-e-Naw.” 2008. NATO.

[17] NATO, “Bucharest Summit Declaration - Issued by the Heads of State and Government Participating in the Meeting of the North Atlantic Council in Bucharest on 3 April 2008.” NATO. 3 April 2008, 23.

[18] Andrew Wolff, “The Future of NATO Enlargement after the Ukraine Crisis.” International Affairs (Royal Institute of International Affairs 1944-) Vol. 91, No. 5 (2015): 1105-1106.

[19] Daniel Treisman “Why Putin Took Crimea,” Foreign Affairs. 18 April 2016.

[21] NATO, “Relations with Ukraine.” NATO. 28 October 2022.

[22] Patrick Reevell, “Amid Ukraine Invasion Fears, Putin Says West Must Give NATO Guarantees,” ABC News, 23 December 2021.

[23] Michael S. Darnell, “American Tanks Return to Europe after Brief Leave,” Stars and Stripes. 31 January 2014.

[24] David Takacs, “Ukraine‘s Deterrence Failure: Lessons for the Baltic States.” Journal on Baltic Security, Vol. 3, No. 1 (2017): 4.

[25] Jane Cordy, “Committee on The Civil Dimension Of Security (CDS) Ukraine: Five Years After The Revolution Of Dignity Report.” 9-11. NATO Parliamentary Assembly. Committee on the Civil Dimension of Security (CDS).

[26] Dr. Lester W. Grau and Charles K. Bartles, The Russian Way of War: Force Structure Tactics and Modernization of the Russian Ground Forces(Fort Leavenworth Press, 2019): 10, 27-32.

[27] NATO, “Wales Summit Declaration Issued by the Heads of State and Government Participating in the Meeting of the North Atlantic Council in Wales.” NATO. 5 September 2014.

[28] NATO, “NATO’s Readiness Action Plan Fact Sheet.” Public Diplomacy Division (PDD) – Press & Media Section – Media Operations Centre (MOC).

[29] NATO, “Whales Summit”.

[30] NATO, “Joint Statement of the NATO-Ukraine Commission,” NATO. 4 July 2014.

[31] Rick Larsen “Special Report: Ukraine’s Fight for Freedom & Allied and Global Response to Russia’s War,” 3-4. NATO Parliamentary Assembly. NATO Parliamentary Assembly Defence and Security Committee.

[32] NATO, “Brussels Summit Communiqué Issued by the Heads of State and Government Participating in the Meeting of the North Atlantic Council in Brussels 14 June 2021.” NATO. 14 June 2021, 30.

[33] Jarrett Renshaw, “Biden Says He Warned Putin of ‘Heavy Price’ over Ukraine,” Reuters, 31 December 2021, sec. Europe.

[34] Michael Schwirtz, “NATO Signals Support for Ukraine in Face of Threat from Russia,” The New York Times, 16 December 2021, sec. World.

[35] Justin Gomez, “Biden Warns of ‘Severe Consequences’ If Putin Moves on Ukraine,” ABC News. 8 December 2021.

[36] Andrew Rettman, “No Obligation to Defend Ukraine from Russia, NATO Chief Says,” EUobserver. 1 December 2021.

[37] “NATO Secretary General with the President of Ukraine Volodymyr Zelenskyy, 16 December 2021.” NATO News. 16 December 2021.

[38] Paul Kirby, “What Russian Annexation Means for Ukraine’s Regions,” BBC News. 30 September 2022.

[39] NATO, 2022 Strategic Concept, 3.

Rebecca Jensen
Rebecca Jensen

Dr. Rebecca Jensen is an Assistant Professor at the Canadian Forces College.

Larry D. Caswell
Larry D. Caswell

Colonel Larry Caswell is a student at the U.S. Army War College.

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