Analysis & Opinions - Belfer Center for Science and International Affairs, Harvard Kennedy School

NATO’s Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA)

  • Stephen R. Covington
| Aug. 02, 2023


At the recent summit in Vilnius, Lithuania, members of the North Atlantic Treaty Organization (NATO) adopted significant improvements to NATO’s deterrence and defence posture to counter Russia.  Underlying these new measures is a new military concept approved in June 2020 – the Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA).  

In this publication, “NATO’s Concept for Deterrence and Defence of the Euro-Atlantic Area,” Stephen R. Covington, one of the main architects of the new military concept, explains the fundamentals of the new DDA concept that is guiding NATO‘s strategic path of modernizing its collective defence system and its response to Russia’s unprovoked attack on Ukraine.  DDA is not a return to the past, but the Alliance making a decisive turn to modern strategy to deter 21st century military threats after decades of crisis response and management operations. This concept is at the heart of the historic military adaptation of the Alliance.

Stephen R. Covington, Strategic and International Affairs Adviser to Supreme Allied Commander, Europe (SACEUR), has helped guide military policy throughout the arc of the post-Cold War relationship between NATO and Russia, from cooperation to confrontation. He has advised 12 SACEURs for 34 years at Supreme Headquarters Allied Powers, Europe (SHAPE) on strategy, policy, international affairs, and partnership.

Kevin Ryan
U.S. Army Brigadier General (ret.)
Former Founder/Director, Belfer Center Intelligence and Defense Projects; former Senior Fellow


In the early 1990s, the Alliance ended the military concept of “Forward Defence and Flexible Response” and embraced a different strategic approach for the organization of military capability with scales of action aligned to the threat posed by diverse forms of instability.  Terrorism, authoritarianism, ethnic rivalries, local conflicts, economic destabilization, natural disasters, and civil wars were the main sources of post-Cold War instability. Alliance case-by-case responses since 1991 to these forms of instability were diverse - as were Alliance operations - each addressing a specific crisis with specific strategic objectives, plans, forces, and operations developed and elaborated concurrent with the crisis.  

The regional and global security environment has changed significantly since 1991.  Russia and terror groups are the Alliance’s two main threats. Other security challenges are intensifying and broadening. NATO’s new Strategic Concept clearly takes into account these changes and affirms the Alliance’s commitment to the security of all Allies and a peaceful Euro-Atlantic Area.  It describes a strategic vision and path to secure Allies now, and into the future.

NATO’s Strategic Concept is supported by a new military concept – the Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA).  Approved in June of 2020, DDA is a strategic redesign of the Alliance’s approach to deterrence and defence that has been relied upon since the end of the Cold War. The DDA military concept aligns to the demands of modern warfare and the security environment, upholds the Alliance’s defensive nature and its war prevention aims, and reflects the Allies' commitment to a stable, rules-based Euro-Atlantic and global order. DDA organizes Alliance deterrence and defence on a strategic scale to protect all Allies from the threats posed by Russia and terror groups. Its approval by NATO Chiefs of Defence and Defence Ministers in 2020, and subsequent endorsement by Alliance Heads of State and Government in 2021, is a powerful demonstration of Alliance political unity and commitment to secure one another in this era of increasing threat and challenge. 

DDA’s peacetime activities and operations in defence are guided by the principles that no country or non-state actor will achieve advantage over the Alliance in capability, readiness, or geography; no Ally will be alone to address the threats and challenges of this era; and every inch of Alliance territory will be defended by all Allies. These fundamental principles are reflected in DDA military activities in peace, crisis, and conflict.

  • Operationally in deterrence, DDA emphasizes that preventing the transition to conflict starts in peacetime, not in crisis, and it requires timely and robust, purpose-driven military deterrence activity to contest attempts by an adversary to accrue military advantage over the Alliance.  Deterring in peacetime also requires integrating multiple instruments of power to contest destabilization and intimidation and prevent its widening.
  • Operationally in defence, DDA holds that NATO force employment in response to aggression requires the integration of mutually reinforcing, robust, multi-domain operations on an operational-strategic scale across the totality of the Alliance area.

DDA impacts Alliance preparedness in numerous ways.  The concept strengthens North Atlantic Council (NAC) political decision making in peace, crisis, and conflict; deepens collective understanding of the threats and challenges; strengthens the preservation of peace through vigilance and purpose-driven deterrence military activities; unites Allies in collective defence strategically, operationally, and tactically through new collective defence plans; and enhances Alliance operational-strategic military flexibility for both collective defence and crisis prevention/management.  

This new strategic military concept is at the center of the Alliance’s unprecedented post-Cold War, strategic-scale adaptation of its collective defence system built on new posture, plans, command and control, and force models. DDA is also at the center of the Alliance’s response to Russia’s unprovoked and unjustified attack on Ukraine.  The DDA strategy contributed to enhanced Alliance speed in building a strengthened Alliance  military posture in the Eastern flank, supported by strategic-scale organization of diverse multi-domain, military deterrence activities across the Alliance. The Alliance’s strengthened posture, built on the key tenets and elements of DDA, has deterred Moscow from expanding or escalating the conflict with Ukraine to a conflict with NATO. 

DDA represents the return of the Alliance to an overarching force employment strategy. Its impact on Alliance armed forces and military activities is far-reaching, and this article describes the key elements of the concept in peace, crisis, and conflict and the major features of DDA implementation.

Elements of the DDA Strategy in Peace, Crisis, and Conflict

DDA reflects an Alliance conclusion that 21st century deterrence and defence aims cannot be achieved through a crisis management approach, and the Alliance required a new strategy to address the security threats and risks of this era. The threat posed by Russian strategic operations and the terror groups’ cycle of operations required a strategy where strategic objectives, operational patterns in deterrence deliberately conducted on a strategic scale, roles and missions of forces in modern defence operations, and forces, plans, and command and control for collective defence are set in peacetime to execute deterrence actions in peace and crisis, and defence in conflict if necessary. The potential speed, scale, and destructiveness of the threats posed to the Alliance led to the change in its strategic approach to deterrence and defence.

DDA guides Alliance peacetime deterrence activities, military responses in crisis to deter aggression, and military operations to defend all Allies at strategic, operational, and tactical levels. These activities and planned defence operations, in turn, are driving Alliance force posture.  The concept was developed at NATO’s Supreme Headquarters, Allied Powers Europe, led by former Supreme Allied Commanders, Europe GEN Mike Scaparrotti (USA) and GEN Tod Wolters (USAF), and developed in collaboration with all Allies. As the first major redesign of Alliance deterrence and defence in three decades, DDA contains five fundamental tenets that shape the Alliance’s approach to deterrence activities and defence operations.

DDA is Strategic-Scale, 360 Degree Deterrence and Defence United by Common Strategic Objectives

The Alliance’s Area of Responsibility (AOR) is an enormous space constituting almost eight percent of the globe, 31 nations, and one billion people.  21st century deterrence requires controlling the Alliance geographic area from its tactical to strategic depths with nations connected, and forces echeloned and organized for defence. Under DDA, the Alliance AOR is a single strategic defence space. This single defence space is not oriented to one region, or one strategic direction, or one threat. It is oriented to the defence of all Allies from threats posed by terror groups’ cycle of operations and Russian strategic military operations, from any direction.

With DDA, the overall defence of the Alliance - its forward areas, European depth, adjacent maritime spaces, and strategic depth to North America - is a single, 360 degree, strategic-scale defence for any contingency impacting the security of a single Ally, a group of Allies, or the Alliance as a whole. DDA’s is a forward defense strategy designed to secure and defend every inch of Alliance territory.  Simultaneously, forward defence areas are connected to the breadth and depth of military capabilities deployed across the entire Alliance area.

Under DDA, military actions in deterrence and defence are Alliance-wide, connected by deterrence and defence objectives, which in turn drive common strategic patterns of military activity in peacetime, and a common organization of NATO-wide posture and defence operations. The DDA concept connects diverse regions, forces, and operations across the AOR, and organizes mutually reinforcing military activities to achieve the Alliance’s fundamental objective of preserving peace. In the event deterrence fails, mutually reinforcing operational-strategic scale, multi-domain operations would be conducted to defend all Allies.This strategic-scale approach, built on a single strategic defence space, brings to bear the totality of Alliance military capability to fulfill the Washington Treaty’s Article 5 obligation to all Allies under all contingencies.

DDA is Nation-wide Defence Approaches, Planning, and Forces in a NATO Strategic Framework

Under DDA’s design, nation-wide defence of individual Allies - national activities in peacetime, national defence plans, national forces, and national operations in crisis and conflict in multiple regions - are connected to Allied regional deterrence activities in peacetime and regional-scale defence operations in conflict.  In turn, multiple NATO regional activities and defence operations are integrated and mutually reinforcing to establish a single strategic-scale defence, under the command and control of NATO’s Supreme Allied Commander, Europe. This strategic approach supports speed and unity in political decision-making by the North Atlantic Council and speed and unity of Allied military action at strategic and operational levels,. 

DDA is Purpose-Driven Vigilance in Peacetime

As a defensive Alliance, the Alliance seeks to preserve peace, prevent the transition of peace to crisis, and deter the transition of crisis to conflict. Under DDA, preventing the transition to conflict starts in peacetime, not in crisis.  DDA reflects the Alliance judgement that 21stcentury deterrence requires collectively contesting in peacetime (including resilience), defence capabilities to deny short-notice conflicts and long conflicts, preservation of preeminence at the operational and strategic levels of war, and preservation of the integrity of the overall Alliance defence system.

This requires military activities in peacetime to contest challengers’ strategies and strategic patterns in domains and in geographic areas to prevent the accrual of decisive military advantage over the Alliance.  Not contesting challengers in domains or geographic space inside the AOR cedes security in peacetime, cedes time for political decisions in crisis, and cedes time and space for military response in crisis and conflict. Deterrence also requires the integration of multiple instruments of power to contest destabilization and intimidation, resolve disorder, and prevent its widening.

Preservation of peace is the highest priority for the Alliance.   General Dwight Eisenhower, NATO’s first SACEUR, designed the SHAPE emblem and it contains the words “Vigilia Pretium Libertatis” – “Vigilance is the Price of Liberty”.  Under DDA, the Alliance has established vigilance activities that are multi-domain and conducted in multiple geographic areas in a deliberate rhythm to communicate Alliance political will and demonstrate the Alliance’s capability to defend all Allies. Consistently executed in peace and united by common Alliance operational and strategic deterrence objectives, vigilance activities reflect the Alliance’s Multi-Domain Architecture in action to secure peace and promote stability across the entire AOR. In the Alliance’s Multi-Domain Architecture, nuclear weapons make a unique contribution to rendering the risks of aggression incalculable and unacceptable, and constitute the Alliance’s ultimate means of deterrence.

DDA’s vigilance activities are organized to deny domain, geographic, and readiness advantages, prevent destabilization and intimidation, and maintain balance and stability. In particular, DDA organizes Allied vigilance activities to contest and deny a potential adversary the advantages it requires to conduct offensive military operations on any scale in any geographic area.  Built on dynamic force readiness and executed across all of the Alliance area, these demonstrations of military capability, strengthen deterrence by posing tactical, operational, and strategic dilemmas to potential adversaries’ calculations of advantage against the Alliance.  This approach to deterrence prevents an adversary from attaining an advantage in peacetime, that could be expanded in crisis, and subsequently exploited in conflict.  In so doing, the Alliance preserves a stable and balanced peace, and prevents crisis and conflict.

DDA is Preventing Crisis from Escalating to Conflict:  Multiple Forms of Reinforcement

In crisis, the Alliance’s fundamental objective is to prevent crisis from escalating into conflict. Countering larger-scale intimidation, countering force buildup in the form of tactical and operational scale concentrations, and countering regional or national mobilization are critical actions taken in crisis to move crisis away from conflict, and back to peace. DDA organizes Alliance military capability to reinforce in multiple forms, at multiple speeds, on multiple scales, and in multiple geographic areas simultaneously.

Reinforcement of forces at speed and at scale relevant to the threat and reinforcement by multi-domain, long-range fire systems from across the AOR constitute major forms of capability that deter an adversary transitioning from force deployment to force employment in offensive operations. Capability to move forces for large-scale defence operations or reinforce posture with long-range fire capabilities across the AOR can undercut force advantage and undercut certainty in offensive operation calculations by an aggressor. Denying advantage, and denying certainty in calculations can compel an adversary to replan operations, and delay the initiation of conflict, and deter the initiation of conflict. Long-range fires also can introduce uncertainty into offensive plan calculations based on local force advantage. Reinforcement by long-range fires can undercut an adversary’s ability to isolate and preserve force advantage in a local battle space due to their ability to influence a local battle space from operational depths and from multiple directions, that are difficult for an aggressor’s offensive plans to predict.

DDA is Operational-Strategic Flexibility and Multi-Domain Operations in Defence Across the AOR

In defence, Alliance military actions in support of political objectives directed by the North Atlantic Council counter aggression to defend every inch of Alliance territory and preserve Alliance domain integrity across the entire strategic defence space of the Alliance. Allied defence operations are organized on a strategic-scale with strategic, operational, and tactical operations and activities interconnected across the AOR.  Robust multi-domain operations with operational-strategic scale flexibility that integrate air, land, maritime, cyber, and space operations are conducted to defend all Allies.  These operations conducted across the Alliance’s geographic space are mutually reinforcing, connected, and organized for multi-variant, multi-speed conflict.

In this concept for collective defence, all geographic areas and all war-fighting domains are connected across the Alliance. National forces and nation-wide defence of one Ally is connected to the defence of all Allies. Regional-scale defence operations form the operational-strategic building blocks of the Alliance’s single strategic defence of all Allies.  These regional-scale defence operations are reinforced by AOR-wide operations from multiple domains. This strategic design for defence unites diverse regions of the AOR, built on a multi-domain architecture, and allows for the flexible conduct of diverse multi-domain operations on strategic and regional scales to defend all Allies.

DDA Implementation:  Modernized Plans, Forces, Alert System, Command and Control, and Exercises

Upon its approval in 2020, NATO initiated a strategic-scale, multi-year program to align Alliance plans, force posture, capabilities, alert system, command and control, and exercises to DDA, called DDA implementation.  This program is modernizing the Alliance’s collective defense system in line with threats and defence operations required to secure all Allies.  ADM Rob Bauer, Chair of the NATO Military Committee has characterized this Alliance transformation as an historic, new era of collective defence.[1]

DDA implementation is improving Alliance military planning with the development of a family of collective defence plans for multi-speed, multi-scale contingencies for the threats posed by Russia and terror groups. The DDA family of collective defense plans include a strategic plan for the defence of the entire AOR; regional plans for the defence of regions within the AOR; strategic plans for individual military domains (air, land, maritime, special operations forces, cyber, and space); and prudent planning for a wide range of contingencies. This new family of DDA plans for modern, multi-domain, integrated defence is an unprecedented level of Alliance planning in the post-Cold War era for the two main threats. Allies will exercise these plans through a modernized DDA exercise program that encompasses both NATO and national exercise programs.

21st century Alliance deterrence requires a force structure that can counter intimidation, counter destabilization, counter mobilization, and counter aggression, and bring to bear the military power of the Alliance to prevail in conflict.  The DDA Multi-Domain Architecture is composed of AOR-wide high readiness and resilience; effective integration of Indications & Warning (1&W), joint forces forward and throughout the AOR, joint fires forward and from the depths of the Alliance; Integrated Air and Missile Defence (IAMD), Cyber, Command, Control, Communications, Computers, and Intelligence (C41), electronic warfare, and space capabilities. Heads of State and Government have directed the Alliance to strengthen readiness, deployability, integration, and interoperability for the full range of forces, capabilities, assets, and infrastructure. These capabilities will be united to address multi-speed, multi-scale contingencies (including reinforcement with forces and fires) at various levels to meet the requirements set by the new strategic military concept and its plans. 

GEN Cavoli, SACEUR, has stated that "the plans that come out of DDA, the strategic plans as well as the regional plans, these will drive our structure, our operations, our activities, and importantly…our investments into the future. And this will include changes in our command and control structures.”[2]  United in new plans and organized on new posture and modernized NATO command and control, the Alliance will further build a flexible, agile, and resilient multi-domain architecture with the right forces in the right place at the right time, and a strengthened command and control tailored to support 360-degree posture. 

This new phase of Alliance force modernization includes national force procurement as well as the implementation of a new NATO force model. The new NATO force model drives the organization of more powerful, fast, and sustainable military forces for all Allied operations, inside or outside the AOR, as directed by the North Atlantic Council.[3] The Alliance is working to ensure that at least 100 brigades, 1,400 fighter aircraft, and 250 ships and submarines are maintained at high readiness. This will ensure high-end capabilities and more ready forces are available for operations in shorter periods of time to execute new collective defence plans.   The force posture and plans are coherent with the DDA strategy and aligned to a new military alert system for Alliance forces. AOR-wide logistics and theatre enablement also are critical parts of DDA implementation. 

The Alliance’s strengthened posture and military activities in response to Russia’s aggression against Ukraine is an example of the DDA strategy in action.  In 2022, Moscow sought to break Ukraine militarily, and concurrently sought to militarily intimidate and damage Alliance political cohesion with their military buildup around Ukraine and deployments in the Alliance’s AOR, including Russia’s large-scale maritime deployments and strategic nuclear exercise in early 2022.  Moscow failed to intimidate or damage Alliance political cohesion.  The Alliance took decisions to strengthen military deterrence actions and posture across the AOR at the speed and scale relevant to the threat, demonstrating to Russia an Alliance united both politically and militarily.  DDA reorganization of AOR-wide peacetime vigilance activities and Alliance adoption of the DDA single strategic defence plan for the entire AOR underpinned the military organization of the Alliance’s reactions to Russia’s force deployments and attack on Ukraine.  

In line with DDA, the Alliance conducted AOR-wide, strategically organized vigilance activities, including Intelligence, Surveillance, and Reconnaissance activities as well as exercises, for several months concurrent with Russia’s nation-wide military buildup. Enhanced vigilance across the AOR was executed concurrent with Russia’s continued buildup in late 2021.  Allies strengthened posture in the Eastern flank under NATO and national command before the onset of Russia’s attack against Ukraine.  This posture was further increased with the activation of NATO Graduated Response Plans in February 2022, and the deployment of elements of the Very High Readiness Joint Task Force.  150,000 NATO land forces, including 40,000 under NATO command, are executing deterrence tasks in the Eastern flank of the Alliance.  The number of battle groups in the east of the Alliance has increased from four to eight, and these battle groups are exercising reinforcement up to brigade level." NATO land forces are supported by significant numbers of air and maritime forces, including air and missile defence capabilities, arrayed strategically and operating across the Alliance to deter aggression.

Unprecedented vigilance activities also have been conducted, including multiple national carrier strike groups operating in the maritime domain across the AOR, three at one time in the Mediterranean Sea, to demonstrate Alliance capability and resolve to defend all Allies.  GEN Cavoli, SACEUR, characterizes the military activities as “multi-domain forces at high readiness in a strategically advantageous posture….. conducting vigilance activities across the AOR to deter Moscow from expanding or escalating the conflict to NATO”.[4]  Current Alliance posture and vigilance activities continue to shield all Allies and deter potential expansion of the conflict by Russia, with Allied forces operating on multiple scales, across all domains, in all regions, at speed, and with common strategic purpose.

Allies decided at the Madrid Summit that the current NATO military posture in response to Russia’s war against Ukraine is the Alliance’s baseline deterrence and defence posture.  Russia’s war against Ukraine, and the threat posed by Russia to Allies, effectively accelerated DDA implementation and set a new baseline for deterrence and defence posture.  On this new baseline, future military posture will be shaped by the integration of the DDA plans, alert system, command and control, capabilities, and exercises.  Taken together, DDA implementation is an historic modernization of the Alliance’s overall system of collective defence to protect Allies now and into the future.

United in Common Deterrence and Defence

NATO's highest purpose, as reflected in the Washington Treaty, is to promote stability and well-being of the North Atlantic Area, and unite efforts in common defence for the preservation of peace and security. Thirty-one Allies are united in their collective defence, connected by the common DDA military deterrence and defence concept.

Allies are united in protecting Alliance territory, collectively contesting threats below the level of armed conflict. Allies are better organized to conduct robust multi-domain large-scale operations in 360 degree defence.  The Alliance defence posture is at its strongest level in two decades – better organized and better prepared – for defence against military aggression.  NATO maintains the requisite capability and flexibility for employment of forces in non-Article 5 contingencies. Concurrently, NATO forces are being modernized.

In this era of heightened threat and intensifying challenge, the Alliance is a stable and strong foundation. As NATO’s new Strategic Concept guides the Alliance through the complex security problems of this era, DDA will strategically organize Alliance military activities and operations in deterrence and defence and shape the Alliance’s future defence posture.  In so doing, the Alliance will be positioned militarily to address an unpredictable security environment with purpose, strength, and unity. 

Stephen R. Covington is Strategic and International Affairs Adviser to Supreme Allied Commander, Europe (SACEUR).  The author has advised 12 SACEURs for 34 years at Supreme Headquarters Allied Powers, Europe (SHAPE) on strategy, policy, international affairs, and partnership.

[1] ADM Bauer Press Conference following 10 May 2023 Meeting of the Military Committee Chiefs of Defence.

[2]GEN Cavoli Press Conference following 10 May 2023 Meeting of the Military Committee Chiefs of Defence.

[3] In addition, NATO Defence Ministers took decisions in February of 2023 to further strengthen the deterrence and defence of the Alliance, which included approving new guidance for NATO defence planning. NATO Secretary General Stoltenberg stated that this decision on new new guidance for NATO defence planning “…reflects the reality that we live in a more dangerous world. With Russia's aggressive behaviour, the persistent threat of terrorism, and the challenges posed by China. It will drive the capability changes for the years to come. And ensure that our deterrence and defence remain strong and credible."

For more information on this publication: Belfer Communications Office
For Academic Citation: Covington, Stephen R..“NATO’s Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA).” Belfer Center for Science and International Affairs, Harvard Kennedy School, August 2, 2023.

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