Nuclear Deterrence 101

What Finland Needs to Know on the Occasion of Joining NATO

Finnish membership in the NATO Alliance is a momentous occasion, both reflective of a shift in Euro-Atlantic security, and itself changing and shaping regional security for decades to come. On the occasion of Finland’s fast-approaching full membership, it is useful to describe the concept of nuclear deterrence, especially NATO’s nuclear deterrent, and what will be expected of Finland regarding NATO’s nuclear deterrent as a full member of the North Atlantic Alliance.


Most simply put, deterrence is a state in which one actor is prevented from taking an action that it desires because it perceives that the other actor can and will take action that impose costs greater than the potential benefit of the action. Deterrence is a sub-set of coercion, where an actor seeks to change the other actor’s perception of the costs and benefits of action or inaction. Deterrence is the brother to compellance, where an actor uses the threat of force to force the other actor take an action.

Deterrence as a concept is universal, such as any concept can be, and is observed in nature (an animal’s roar or growl) as in antiquity (“si vis pacem, para bellum”). Conventional deterrence is a common phenomenon, as nations chose not to initiate war, due to judgements of the cost and benefits. However, conventional deterrence entails great risk, as “only battle itself yields a definitive judgement about the balance between competing conventional forces.”

The advent of nuclear war changed the calculations of nations, as the damage from a nuclear attack would be so horrendous as to make the avoidance of war with a nuclear-armed state a goal in and of itself. It is hard to overestimate the psychological shock on leadership at the time of being able to create an explosion with a single bomb that could erase an entire city from the face of the earth. This new weapon, and its quick spread to the other nuclear weapon states, shifted strategies decisively in the US and Soviet Union away from warfighting towards avoiding general war between the sides.

Within the concept of nuclear deterrence, however, there are two distinct concepts often discussed today – 1) deterrence by punishment (also known as Passive, or Type I Deterrence), based on the fear that an actor taking an action would result in a devastating retaliatory blow that denies the actor of benefit, and 2) deterrence by denial (also known as Active, or Type II Deterrence), based on the idea that the other side would be able to act to prevent the actor from reaching its goal in the first place. These definitions were worked out during the Cold War, and became central to the strategy of preventing war between the United States and the Soviet Union, and later between NATO and the Warsaw Pact. Of course, one side effect of establishing a clear line of deterrence – where neither side seeks to attack the other directly – also incentivizes attacks below the line or up to the line. Hence, although deterrence held through the Cold War, that period included both direct and indirect confrontation between the US and the USSR, including the weaponization of economics, energy, and information to undermine each other, as well as global proxy wars between the two sides.

A Bulgarian chemical, biological, radiological and nuclear (CBRN) technician decontaminates his comrade following a hazardous materials sweep near Ohrid, North Macedonia during NATO's consequence-management exercise North Macedonia 2021.
Photo: NATO

NATO Nuclear Deterrence

NATO’s nuclear deterrent was established in 1949 to respond to the threat of an imminent Soviet invasion. At the time, the Soviets had the “overwhelming preponderance of immediately available military power on the Eurasian continent and a consequent capability of resorting to direct military action at any time” and the US therefore sought to prepare its nuclear forces to deter the Soviet Union from initiating an overwhelming conventional attack. Allies agreed to this deterrent strategy in the first NATO Strategic Concept in 1949, which pledged to “insure the ability to carry out strategic bombing promptly by all means possible with all types of weapons, without exception.” This strategy was updated in 1950, “to convince the USSR that war does not pay, and should war occur, to ensure a successful defense,” with “all types of weapons, without exception.” Even this strategy was deemed inadequate, causing the US to forward deploy nuclear weapons in Europe, with the first weapons arriving in the UK and West Germany in September 1954, for use by US forces, and the first sharing of US nuclear capabilities with Allies agreed and announced in December 1957. This decision to share nuclear capabilities comprised of the ability of Allies to launch nuclear weapons under US command, including nuclear land mines, artillery shells, short-range rockets, free-fall bombs, and intermediate-range ballistic missiles, all  under the direct command of SACEUR. Note that the weapons would remain under the command and control of the US, and only be released to Allies for delivery upon the command of the US President, and then under war plans directed by SACEUR. Thus, NATO as a whole could “use atomic and thermonuclear weapons in their defense from the outset,” of a conflict with the Soviet Union, with an “instant and devastating nuclear counter-offensive by all means available”. The US sought to assuage European concerns about a lack of voice in nuclear employment in war through the Athens Guidelines of 1962, which allowed for NATO nuclear consultations, including an Allied veto over initial nuclear use. However, NATO still had no permanent body specially tasked to make decisions on nuclear policy.

To address this gap, NATO created the Nuclear Defense Affairs Committee (NDAC), open to all Allies, and subsidiary Nuclear Planning Group (NPG), open to the seven Allies then participating in the nuclear mission, in December 1966. France refused to participate, as it had withdrawn from the military command structure of NATO earlier that year, and despite returning in 2009. The NDAC and NPG set NATO nuclear weapons policy and plans, and handled the tactical issues of communications, safety, transportation, and exercises. Work in the NDAC and NPG led to NATO agreement on a new defense concept for the Alliance, known as “Flexible Response.” This new nuclear doctrine included tailored use options meant to prevent the Soviets from controlling escalation, and inspiring debates on the conditions for first use of nuclear weapons (called the Provisional Political Guidelines) which continued until the end of the Cold War. It also allowed NATO to begin reducing its stockpile from its peak of 7,000 weapons. The final major innovation in NATO structures was the creation of the High-Level Group (HLG) of the NPG in October 1977, designed to give the US chairmanship over a body with nuclear planning and employment decisions. Allies also agreed to merge the merger of the NDAC and the NPG under the NATO Secretary General’s leadership, and open to membership in the NPG to all Allies.

After the end of the Cold War, NATO revised its nuclear doctrine, vastly reducing the number and types of forward-deployed sub-strategic nuclear weapons, and steadily reducing their role in NATO defense from 1991 to 2014. Allies agreed in the 1991 Strategic Concept that “the circumstances in which any use of nuclear weapons might have to be contemplated by them are therefore even more remote,” and began the process of reducing the number and types of nuclear weapons assigned to the forward defence of the Alliance. Today, these weapons include fewer than 200 US B-61-12s stationed in Europe (the number and locations stored are both classified and must never be confirmed by Allies), as well as the UK submarine-launched ballistic missiles if and when the UK Prime Minister authorizes their use on a NATO nuclear mission. NATO policy is that the UK and France’s nuclear weapons “contribute to deterrence by complicating the calculations of potential adversaries”, however, UK nuclear weapons are integrated into NATO defense planning and France’s are not.

Reflecting deep divides on the trajectory of Russia, the NATO 2010 Strategic Concept introduced the idea that deterrence is “based on an appropriate mix of nuclear and conventional capabilities,” intended to introduce ambiguity among Allies seeking disarmament from those that continued to seek deterrence. This argument soon required a Deterrence and Defense Posture Review (DDPR) in 2012, which papered over divide disagreement, and included the commitment to maintain “an appropriate mix of nuclear, conventional, and missile defence capabilities for deterrence and defence”. Starting with Russia’s illegal annexation of Crimea, NATO’s nuclear weapons policies have strengthened considerably from 2010. Starting with the 2014 Wales Summit Communiqué, Allies reversed the minimization of the role of nuclear weapons in NATO defence, culminating in the 2022 Summit and Strategic Concept. Now, NATO doctrine is that it will ”impose costs on an adversary that would be unacceptable and far outweigh the benefits that any adversary could hope to achieve,” a clear return to the original concept of deterrence in general, and NATO deterrence in particular. However, it retains a minimal nuclear posture.

A U.S. Air Force 509th Bomb Wing B-2 Spirit, capable of delivering both conventional and nuclear munitions, approaches KC-135 Stratotanked during training exercise over England August 29, 2019.
Photo: Staff Sgt. Jordan Vastelan / USAF

Expectations of Finland

There is no obligation for NATO members to participate in nuclear planning, nor to host NATO forces (including nuclear weapons), exercises, or permanent or temporary deployments on its territory. Each Ally decides for itself whether or how to participate in NATO activities according to its own national laws, policies, and procedures. In addition, all Allies can veto NATO decisions, known as “breaking silence”, as part of the consensus principle, including on nuclear employment. Finland is expected participate in decision making in the NPG at the level of the North Atlantic Council, where the Ambassadors represent the Heads of State and Government, in nuclear decision-making. These decisions include, in extremis, decisions on the employment of nuclear weapons assigned to the defense of the Alliance (France abstains from such decisions).

The extent of Finnish participation in NATO’s day-to-day and wartime nuclear posture and decision-making is up to Finland, including political and military dimensions. On the political side, Finland will be expected to participate in nuclear planning and decision-making at NATO Headquarters, SHAPE, and other NATO commands. At the same time, it will be expected to take up political burden-sharing, including defending NATO in international bodies where it is criticized, for instance, in the United Nations and the Nuclear Non-Proliferation Treaty review process. Defending NATO’s nuclear sharing arrangements is an important contribution all Allies can make, but not all Allies have raised their voices in the past. Membership in the two NATO decision-making bodies on nuclear policy, the NPG and HLG, will be expected, though this is not required. For instance, France does not participate in nuclear planning at NATO, and Greece dropped out in 1974 (returning in 1980). Sweden already has committed “to participate fully in NATO’s military structure and collective defence planning processes and is willing to commit forces and capabilities for the full range of Alliance missions,” which has widely been read as full participation in all aspects of NATO’s nuclear mission short of basing and delivery.

The NPG falls under the authority of the Secretary General, and sets NATO nuclear policy, overseeing safety, security, survivability, communications and deployment, and interacts with the Committee on Proliferation (CP) and Arms Control, Disarmament, and WMD Non-Proliferation Committee (ADNC) to coordinate arms control and nuclear nonproliferation policy. The NPG can be chaired by the Assistant Secretary General of the Defense Policy and Plans Division, or the Director of the DPP Nuclear Policy Directorate, depending on the level of tasks and decisions. The HLG is chaired by the United States (by the Deputy Assistant Secretary of Defense for Nuclear Matters), and advises the NPT on nuclear policy, planning, and force posture, as well as weapons safety, security, and survivability matters. The NPG and HLG also meet at the working level on a regular basis, at the level of Defense Ministers twice a year, and can meet at the level of Heads of State and Government – although this is a rarer occurrence. Thus, Finland will be expected to make decisions related to nuclear policy, doctrine, posture, safety, security, survivability, and communications.

On the military side, Finland will participate in NATO’s Defense Planning Process, which will require agreeing upon a Level of Ambition for the defense of the Alliance, an Agreed Intelligence Assessment on threats to the Alliance (MC161), the military implementation of the Strategic Concept (MC400), and the modification to the standing defense plans – known as the Graduated Response Plans (GRP Eagle Defender is the plan for Baltic defense). These discussions will, inevitably, include decisions on nuclear weapon use in defense of Allied territory – including whether and how to use such weapons in the defense of Finnish territory. Finland also will be required to decide whether and how to participate in NATO nuclear exercises and missions, including the SNOWCAT (Support of Nuclear Operations With Conventional Air Tactics) mission, where all Allies can provide conventional support to nuclear strikes – including escorting dual-capable fighters, providing surveillance and security, and refueling, and Exercise STEADFAST NOON, an annual exercise of the SNOWCAT mission. Finnish acquisition of the F-35 Joint Strike fighter may increase expectations of participation in STEADFAST NOON and SNOWCAT as a non-nuclear sharing Ally.

It is important to repeat that there is no expectation of hosting, either permanently or temporarily, NATO nuclear weapons on Finnish territory. Several Allies have legal or political commitments, including unilateral pledges, legislation or constitutional bans, on the peacetime presence of nuclear weapons on their territory, including Iceland, Lithuania, Denmark, and Norway. In war, these may change, and NATO’s policy of Neither Confirm Nor Deny (NCND, wherein the US and NATO do not confirm or deny whether nuclear weapons are associated with any individual delivery system, vessel, base, or location) allows a degree of flexibility, particularly in transit and emergency.



The degree to which Finland and Sweden participate in the NATO nuclear mission will be a closely-watched affair. Finland will be expected to fulfill their full range of political and military obligations, including participation in decision-making, as well as in conventional contributions to exercises and missions. However, these expectations do not extend to include the hosting of NATO nuclear weapons on Finnish territory, nor for Finnish aircraft to deliver them. The question of political burden-sharing – whether Finland vocally defends the NATO Alliance in international fora, also remains to be seen. Ultimately, these are important decisions for Finland to make in the coming months, as the final ratifications of Finland’s membership are deposited in Washington.


William Alberque is the Director of the Strategy, Technology, and Arms Control Programme at the International Institute for Strategic Studies in Berlin, focusing on national security strategy, nuclear deterrence and non-proliferation, arms control, risk reduction, and international security, and NATO. He previously served as the Director of NATO’s Arms Control, Disarmament, and Non-Proliferation Centre, and worked for the US Government for more than two decades on nuclear security and safeguards, WMD non-proliferation, arms control, CSBMs, SALW, CBRN defense, pandemic response, and nuclear accident response.

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