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.