U.S. security policy in North Central Europe is based on deterrence by punishment. As in the rest of its global alliance network, American extended deterrence in this region functions on the premise that the United States will be able to defeat the local challenger through devastating counterattacks. As for U.S. allies in Asia-Pacific and the Persian Gulf, the credibility of guarantees to Poland and the Baltic states has rested on the wide supremacy of U.S. military power—not only its large strategic nuclear arsenal but the “overmatch” that U.S. conventional capabilities have been thought to provide in counterattacking any aggressive move. Even more than in other regions, however, the viability of U.S. security in the Baltic has been based on faith in these abilities as, uniquely among U.S. frontier allies, the United States has not maintained even symbolic troop presences in countries east of Germany. Given the parlous state of the Russian military and the vast superiority of NATO, it has been assumed that this setup, involving retaliation in its most unsubstantiated form, would be sufficient to secure the vulnerable states of this region well into the twenty-first century.

This is no longer a safe assumption. The North Central European security environment has evolved in dramatic and unexpected ways that pose significant challenges for the continued solvency of a punishment-based deterrence. First, the local rival’s military is proving to be better armed and led than we anticipated. Long discounted as backward, the Russian armed forces under Vladimir Putin have undertaken major technical and tactical improvements and incorporated important lessons from the Georgia War. The Kremlin has pursued a multi-year, $700 billion defense modernization program that is bearing substantial fruit in Russian military operations in Syria. Its forces outstrip in size and quality any force between itself and Germany, outnumbering NATO’s CEE militaries, combined, by 3:1 in soldiers and 6:1 in planes. In the Baltic region, it has a 10:1 edge in troops and maintains air dominance over NATO’s northeastern corner.

Meanwhile, the forces that the United States would need to draw upon to correct these imbalances are shrinking. U.S. defense structures have been cut to their lowest levels since before the Second World War. In Europe, they have dropped from 300,000 troops to 60,000. The Obama administration has accelerated this process, removing fifteen bases and the most combat-ready units, including two Brigade Combat Teams (BCTs), two air squadrons and all remaining U.S. heavy armor. These drawdowns mean that CEE will continue to be characterized by unfavorable force ratios for the foreseeable future.

Second, Russia is developing tactics for evading retaliatory deterrence. The limited-war techniques used in eastern Ukraine consist of “jab and grab” land incursions designed to avoid the traditional triggers of NATO’s Article 5. These techniques operate below the threshold of deterrence by punishment and seek to create territorial faits accomplis that lower the costs of revisionism. Russia backs its stealthy battlefield methods with a tactical nuclear arsenal that exceeds that of NATO by a 27:1 margin, deployed under a doctrine of limited strikes for strategic effect. The combination of limited war and escalate-to-deescalate nuclear warfare poses serious problems for deterrence by punishment. It makes aggression less identifiable (and therefore punishable) while wresting away the presumption of escalation dominance upon which effective retaliation is based. In a limited-war setting, punishment quickly morphs into compellence: not just dissuading an enemy, but dislodging him. This shifts the psychological burden of conflict—fear of retaliation—away from Russia and places it on the shoulders of NATO—fear of escalation. It puts the latter in the position of perpetually under-responding to ambiguous provocations (and thereby losing control of strategically vital spaces by default) or over-responding (and risking war).

Doubling Down on Punishment

So far, America’s response to the erosion of its security mechanisms in North Central Europe has been “double down” on deterrence by punishment. The effort to provide strategic reassurance to the Baltic states and Poland through the deployment of U.S. trip wires represents an attempt to strengthen the trigger mechanisms of retaliation. Similarly, the designation at the Wales NATO Summit of faster response forces is, at heart, an effort to improve the West’s capacity for effective retaliation after an attack has already occurred. Such measures are likely to yield some positive results. The problem with both is that Russian techniques have rendered the very premise of effective punishment invalid. “Little green men” can go around the U.S. infantry company meant to serve as a trip wire. Crimea-style tactics can seize territory in minutes and hours, while even the fastest reaction units require days.

While maintaining the edifice of punishment, the time has come for the United States and its allies to add a new component to the logic of U.S. extended deterrence in the Baltic region: denial. Unlike punishment, which threatens to hurt someone after he attacks you or your allies, deterrence by denial seeks to make it physically harder for someone to attack you. Denial operates on the basis of cultivating fear in the mind of an aggressor that he will have to bear a degree of pain that exceeds whatever gains he hoped to achieve by taking the offensive. Historically, great powers have often used denial to protect valuable allies or territory located near a predatory rival. Prior to the nuclear era, denial was a more common way to achieve extended deterrence, since the tools for projecting military force were less reliable. When facing rivals that were stronger on the ground or far away, it was often more effective to impede their expansion in the first place rather than threatening to punish them after the fact.

Denial: Quills and Pills

There are two ways to accomplish denial. The first is to make it harder for an attacker to take territory. This usually involves equipping a targeted state with defensive weapons to increase its odds of delaying or fending off an attack by a superior force. In the seventeenth and eighteenth centuries, France used subsidies, military advisors and units and technology transfers to prop up a line of mid-sized frontier states (Sweden, Poland and Turkey) that impeded the westward military expansion of Russia. The key to this strategy is that a strong patron must provide access to either a level or quantity of defensive properties that the targeted state would otherwise not possess. Such a strategy is particularly effective in the contemporary battlefield environment, as a growing array of inexpensive military technologies favor the defense. Examples of tools that could provide the “quills” to a North Central Europe porcupine strategy include:

1.   Antitank weapons: Large armored deployments like those used by the Russian Army in Ukraine are vulnerable to antitank weapons, which are mobile, concealable and cheap. Notable examples cost between two and two hundred thousand dollars apiece. As shown in Ukraine, the very knowledge that a defender possesses such weapons can slow an enemy advance.

2.   Anti-infantry rockets: Small militaries facing more numerous opponents can increase their firepower using improved antipersonnel assault shoulder weapons. Such weapons are accurate, lethal and produce an outsized effect in undermining enemy troop morale.

3.   Pre-targeted artillery: Modern artillery methods offer a highly effective area denial method. Artillery can saturate pre-targeted zones with antipersonnel or antiarmor rounds, denying mobility to the advancing force. Concealed artillery forces are survivable and effective deterrents that channel attacking forces into favorable defensive zones.

4.   Air defense: A crucial component in denial is the ability to inflict casualties on enemy air attack capabilities. The advanced air and missile defense (AMD) system sought by Poland is an upper-tier example of such a system. Numerous options exist for strengthening lower-tier defenses, including various Man-Portable Air-Defense Systems (MANPADS). Losses of Russian combat aircraft in the Afghan, Chechen and Georgian wars are a testament to their effectiveness.

5.   Flooding and channeling: The flooding of transit routes is an age-old method for reducing an attacker’s mobility. The impact of eastern Ukraine’s waterlogged landscape on 2014 Russian military offensives illustrates how water can amplify the effectiveness of small units against larger forces. Flooding would be relatively easy to implement in parts of the Baltic region and eastern Poland, and would pose significant engineering problems for advancing ground forces, while exposing attempts to bypass or drain flooded areas. Used in tandem with pre-targeted artillery, flooding could channel and bottleneck attacking forces.

6.   Land mines: U.S. allies in North Central Europe are signatories to the 1997 Mine Ban Treaty and 1980 Convention on Certain Conventional Weapons. However, there are important exceptions to these treaties. Antitank mines are effective, low-cost, hard-to-detect counters to superior armored forces such as those favored by the Russians that not regulated by any treaty. Their use can supplement mobile antitank capabilities in channeling attackers into pre-sited areas. Directional antipersonnel mines detonated by an operator are also not banned, and can be grouped to detonate in key defensive areas by a concealed observer.

A second type of denial is to make it harder for an opponent to keep whatever territory he takes. Historically, this “bitter pill” strategy has often been employed by states that are too small to mount an independent defense but possess the willpower to resistance for long periods of time. Since the ultimate goal of revisionist powers is to achieve quick, easy grabs, this strategy seeks the opposite: to show an attacker that any attempted conquests will be prolonged and costly. Sixteenth-century Switzerland is one example of a small state employing a “bitter pill” defensive strategy; twentieth-century Finland is another. Both used scrappy defensive techniques and small but well-trained forces to advertise their indigestibility to potential predators.

The key to this strategy is the small state developing and honing both the capabilities and mindsets for long-term resistance well in advance of a conflict. This requires the development of standing irregular forces that could be employed at short notice to bleed, delay and harass an occupying army. Such forces differ from regular military units in being smaller, more loosely organized and trained for insurgency warfighting. There is a long tradition of such forces in Europe’s eastern marches, ranging from the Habsburgs’ use of Pandurs and Grenzers to defeat the Turks, Polish employment of irregular cavalry to defeat the Soviets in the 1920s and Lithuanian partizanai sustaining the fight against the Soviets into the 1950s.

To varying degrees, all four U.S. allies in North Central Europe possess nascent paramilitary units and supporting cultures of national resistance upon which to build sophisticated insurgency strategies. Finland is the most advanced in its cultivation of irregular warfighting abilities as a component of deterrence. One of the reasons the Finnish model works so well is its professionalization. Finnish irregular units are organized by the state and receive instruction in advanced insurgency tactics. A balance is struck between instruction and retaining the panache and decentralization that constitute such forces’ main advantages in the field. They are equipped by the government and maintain a professionalized officer and NCO corps that can serve as the backbone for a larger force. By comparison, irregular units in other North Central European states remain embryonic, being either reserves to the national army (as in most of the Baltic states) or unintegrated with national defense structures (as in Poland, where the ministry of defense only recently recognized the 120-odd paramilitary units).

Another reason the Finnish model works well is its high readiness. As in Israel, members of the paramilitary and territorial forces keep their equipment at home for quick access in a crisis. Their government-provisioned weapons are pre-positioned at key points and strongholds across the country. Arsenals provide an infrastructure for wider national resistance in wartime, as successive generations accumulate military experience and theoretically would have ready recourse to cheap and abundant munitions for maintaining francs-tireurs over extended periods to impede an invading force. Given the often-cited centrality of logistics to war, the designation of substantial military resources with a supporting network of provision is crucial for signaling that a country’s commitment to resistance is rooted in a serious strategy and not just a matter for amateur weekend rifle clubs.

A third feature of Finland’s irregular fighting ability is its size. At 350,000 reservists (out of a population of five million), the country’s paramilitary and territorial troops comprise a large latent power of resistance. These forces are fed by universal male conscription and can draw upon the participation of the nation in wartime. The irregular forces of other North Central European states are small, ranging from 45,000 for Poland to a few thousand in each of the Baltic states. A national mindset of resistance is an integral component to deterrence by denial for small states. This requires not just the physical resources but the political commitment to cultivating a “nation-in-arms” mentality among the citizenry. Such an approach could be particularly effective in the Baltic states, where legacies of resistance remain strong at the popular level.

An especially important dimension of the “bitter pill” strategy is advertising it to a would-be attacker. The Finns find ways of communicating to Russia that they are able to make any war bitter and protracted. They do so through carefully placed newspaper articles and highly publicized acquisitions of advanced weapons for enhancing insurgency warfighting. For other North Central European states, expanding the ability to wage this kind of warfare and communicating that ability well in advance of a conflict should be important defense goals in coming years. Doing so would further the aim of deterrence by signaling that any gains of aggression will come at a steep price—a message that the Russian military, with its aversion to Chechnya- and Afghan-style conflicts is likely to note.

Costs of Denial

Incorporating a “quills and pills” approach into North Central European deterrence would not require the United States or its allies to divert significant attention away from more traditional strategic reassurance measures—or eventually, large and permanent NATO basing for the region. Nor would it prevent key states in the region—notably Poland—from also pursuing offensive-oriented approaches to national defense (for a skillful presentation of the case for allies possessing offensive capabilities, see Jakub Grygiel, "Why Frontline States Need Offensive Weapons," in Mitchell and Grygiel, eds., Frontline Allies). It would, however, require certain shifts in mindset for allies as well as the United States. For America, it would mean changing the way we think about the use of our own forces in North Central Europe. Unlike the “trip wires” used for deterrence by punishment, which are understood to have low survivability and simply trigger reprisal, the purpose of troops deployed for deterrence by denial is to live and penalize the attacker. Hence, more thought should be given to what kinds of U.S. forces are sent and, most importantly, how they are tactically integrated with local forces.

The latter must possess the levels of training, matériel and morale required to conduct denial on a modern battlefield. That in turn requires the United States to embrace a less passive approach to arming and equipping its allies. For example, Estonia’s recent procurement of Javelins (120 launchers and 350 missiles for service by 2016) could be doubled or tripled under renovated U.S. foreign military aid programs at a low cost to the United States and high potential return in discouraging Russian adventurism. A systematic review of the weapons that the Ukrainian military learned it needed for a more effective defense (generally, a combination of antitank missiles and light vehicles to create “poor man’s armor”) could pinpoint targeted areas where the United States can be equipping its frontline NATO allies. Units returning from ISAF can be used to instruct local units in techniques used by insurgents.

Embracing deterrence by denial also holds implications for allies. At a basic level, it implies a deeper commitment to local defense than some of these states have so far been willing to embrace. This means not just higher spending, but spending on certain kinds of weapons instead of others and concentrating more national defense resources on the most likely trouble zones (the essence of denial). This is an especially important consideration for states like Poland that still keep most of their heavy forces in the western portions of the country as a result of Cold War–era basing structures. It also means embracing a doctrinal mindset that prioritizes territorial defense. This is not without political risk, as it constitutes a heterodoxy to the longstanding belief in NATO that member-state militaries must be prepared for out-of-area missions. In the post-Crimea environment, such capabilities have low utility for states in North Central Europe. While some dual-use capabilities do exist, the combination of small defense budgets and a newly hostile neighborhood environment should lead to increasing specialization toward local defense rather than attempting to fulfill both purposes. Over time, this will require a doctrinal shift for the NATO alliance, which the United States and its allies should jointly encourage for all but the largest western European militaries. Whatever perceived value the United States may lose through less expeditionary-capable CEE allies will be offset by the benefits of a more stable and well-defended European frontier.

Benefits of Denial

For America and allies alike, incorporating denial into the deterrence for North Central Europe would help to focus scarce resources to the places where conflict is most likely to occur. Technologically, it would play to many areas of advantage for defense in the modern battlefield. In tactical terms, it would lead to deployment of more tools that, should deterrence fail, are more easily redirected to the fighting and winning of a conflict than those used for punishment. Organizing North Central European states for stronger self-defense would raise the visible costs of revision without necessarily adding commensurate defense burdens for the United States. Bolstering denial capabilities of frontline allies enables America to concentrate its resources on upper-tier punishment. Critically in the current Baltic security setting, stronger and more visible frontline weapons and troops would help to amplify the trigger mechanisms for deterrence by punishment, whose vagueness at present is a major propellant to the effectiveness of Russia’s limited war methods.

Perhaps most importantly, a greater focus on denial could help to shift the psychological burden of twenty-first-century conflict in North Central Europe where it belongs: onto the shoulders of an authoritarian state that wishes to rearrange the established order. Where limited-war techniques enable revisionists to believe they can avoid triggering retaliation and thereby get away with an easy victory, deterrence by denial signals that they will pay a price for aggression at the place it occurs, ranging from a sharp rebuff to a war of attrition. The aim in North Central Europe should be to limit options for easy revisions and to increase the immediate cost and difficulty of grabbing and holding territory. Building up such mechanisms will help the United States avoid the predicament of holding together through compellence what it could not through deterrence. The goal should be to instill a healthy sense of fear in Russia of the penalties for aggression. Doing this now, while Russia is mulling its regional options, will be a far cheaper policy in the long run than waiting for deterrence by punishment to fail and then trying to regain lost ground through coercion.

A. Wess Mitchell is president of the Center for European Policy Analysis. This article first appeared as a chapter in Wess Mitchell and Jakub Grygiel, eds., Frontline Allies: War and Change in Central Europe, November 2015​.

Image: Flickr/U.S. Army Europe