Of the many grim lessons from Russia’s war of conquest in Ukraine, perhaps the grimmest is that 21st-century state-on-state warfare will continue to cause exceptionally high losses of soldiers and equipment. Estimates of military casualties recently passed an estimated 100,000 killed and wounded soldiers for Ukraine and as many as 180,000 for Russia, along with thousands of destroyed tanks, aircrafts, and other major weapons systems. To make matters worse for both Russians and Ukrainians, these losses have disproportionally affected elite units and their most modern gear and equipment.
Consequently, a country’s ability to rapidly reconstitute a military force suffering from such casualties will be a key factor in sustaining any similarly intense state-on-state fight in the 21st century. Notably, the two combatants have not only been able to absorb and replace their horrendous losses, but they have even expanded their forces in the field. Ukraine, for example, started the war with 33 maneuver brigades and has added around nine additional brigades since then. Russia has likely doubled the number of soldiers deployed in the war in the six months since its announcement of mobilization, even if the overall quality of Russia’s force declined.
In part, what enabled the two sides to regenerate forces so rapidly is that they can call on a large pool of reservists generated by a system of mandatory military service that still exists in both countries. According to data from Military Balance+, Ukraine has approximately 900,000 available reservists with active military experience within the last five years, whereas Russia can rely on a 2 million-strong reserve. Russian reservists, however, are mostly inactive—that is, they generally do not participate in any training after their regular active duty. (In 2021, Russia launched a new program meant to expand the combat-capable reserve component, but the start of the war halted recruitment.)
A portion of Ukrainian reservists did get called up for training before the start of the war, but the vast majority of reserves have also been inactive, and their overall quality is mixed. Nonetheless, some of these reservists had plenty of experience as soldiers, including through combat tours in eastern Ukraine, where fighting has been ongoing since 2014. Without mass conscription and its support structures, both sides’ ground forces would be suffering from a massive decline in military capacity at the current stage of this war of attrition. This is not only because it takes much longer to instruct civilians in military basics than retraining former conscripts but also because the existing conscription system provides Ukraine and Russia with at least a rudimentary organizational structure for mobilizing and absorbing large numbers of reservists.
It is thus unsurprising that the war in Ukraine has reignited a debate across much of Europe about military conscription, which most NATO countries suspended in the two decades after the end of Cold War. Among NATO’s 30 European member states, only Denmark, Estonia, and Greece currently require mandatory military service. But Germany’s new defense minister, Boris Pistorius, recently said it was a “mistake to suspend compulsory military service” in the Bundeswehr, Germany’s military. Other German politicians have since followed suit. The Dutch defense ministry has been studying the possible introduction of a conscription-style system, with the debate gaining increasing urgency. Mandatory military service was also an issue during Italy’s general election last year.
While Poland debated and ultimately dismissed calls to reintroduce the draft, conscription resumed in Latvia in January—for the first time since it was suspended in 2007. Denmark, in turn, plans to expand its existing compulsory military service for men to include women as well. When one talks to force planners in select European countries, they say what is partially driving this debate is not just difficulties in meeting recruiting targets but also the realization that even the largest military powers in NATO, such as Germany or Poland, would have a tough time sustaining a casualty rate similar to what Ukraine suffered in the first few weeks of Russia’s invasion while still fielding an effective fighting force.
Reinstating full military conscription may not be the best practical answer for most NATO states to increase hard power. First, it would need to overcome staunch political opposition in much of Europe and would be financially challenging. German Finance Minister Christian Lindner has already called the debate a “discussion about ghosts” while Polish Defense Minister Mariusz Blaszczak sees no need to bring back the draft.
Second, reintroducing military conscription would take time, since it requires a major organizational overhaul of European forces’ current structure to accommodate conscripts. This includes a cadre of new instructors; the construction of new screening, processing, and training facilities; and basic military equipment that would eat up defense budget increases for at least a decade. Third, it is unclear whether a full embrace of the draft would produce the force NATO needs in terms of military effectiveness and combat power in Europe. An expansion of military capacity by increasing force size might leave little room to develop capabilities, such as new technologies and weapons systems, and it could undermine force readiness.
Consequently, instead of returning to full conscription and wasting precious time and resources in restructuring and reorganizing European NATO forces, other ways to help increase Europe’s ability to regenerate combat power during a high-intensity conflict should be examined. The first aspect in this regard is the reserve components of European NATO forces. Every European military has a reserve designed to be called up under national security emergencies, including when there is a danger of impending military conflict, to complement active-duty troops. Among European NATO members, however, the reserve system is in severe need of reform. There are neither enough reservists nor do they train often enough, whereas the training they do receive does not prepare reservists for large-scale, high-intensity warfare like in Ukraine now. (For that matter, not even active-duty forces have proper training in most European NATO countries.)
In a conscript force, the reserve plays a crucial role. Only when they call up reservists do units attain their full fighting strength. For example, the conscription-based Finnish military only has an active-duty force of 19,250 people, of whom only a small nucleus are professional soldiers. But Finland can draw on a reserve of 238,000 people. Every year, two conscription cycles with 9,000 recruits each maintain this mobilization strength for the event of war. The advantage of a force structure built around conscripts is that it enables a steady flow of replacements. It also makes it possible to field a relatively large force for territorial defense. The disadvantage is that the combat readiness of such a force can only be maintained through rigorous training and large-scale exercises. In Finland, 18,000 reservists are called up each year for training, although there can be gaps of up to five years between these programs, significantly reducing their effectiveness.
Professional armed forces, such as those of most European NATO members today, combine long-serving volunteers and shorter-term contractors, and they do not maintain large reserve forces. One reason is that this much smaller force is supposed to be at close to full wartime strength at all times. Reservists, who are also volunteers and have served in the same smaller structure, logically make up a much smaller component than a conscript force. Over the last two decades, force planners in Europe focused on expeditionary, counterinsurgency warfare, such as the conflicts in Afghanistan or Iraq—not large-scale, state-on-state warfare—and did not consider it necessary to maintain large reserves. Nor was it financially feasible to keep a large reserve structure in place: All-volunteer reserves cost significantly more than a conscripts-based force since they must be financially incentivized to serve. Due to civilian job opportunities and the relatively low prestige of soldiering compared to the United States, European militaries have also had a tough time attracting enough volunteers.
As a result, European NATO militaries cannot draw on a pool of reservists big enough to maintain combat effectiveness for very long in any large-scale, high-intensity warfare scenario. For example, less than 10 percent of a tank or infantry battalion’s soldiers who are either killed, wounded, or captured could render the entire unit combat ineffective—with not enough reservists available to refill the ranks. According to data from the International Institute for Strategic Studies’ Military Balance+, France fields an active force of just over 200,000 soldiers, plus a reserve of 41,000 people. Germany has 183,000 troops and a reserve force of a little over 30,000 people. Italy has an active force of around 161,000 people and a minuscule reserve force of 17,900 people, while Poland has around 114,000 active-duty soldiers and a reserve force of about 36,000 people.
Among larger European military powers, only Britain fields a sizable reserve component relative to its active-duty force, with around 153,000 professionals and a 75,000-strong reserve. A major issue is that the reserves in many countries are no longer structurally embedded with active forces. Active units no longer contain entire reserve formations periodically called up for training, which has created a divide between the two components and a lack of expertise in how to integrate and effectively use reserves. There is also no uniform approach for how reservists are used. Some reservists are formed in territorial defense units, others complement existing active-duty formations, and still others temporally fill holes among active-duty personnel.
In addition to the small size of reserves, training is a major issue. No large European country, except perhaps Britain and Poland, has a system like the United States’, with its large U.S. National Guard and reserve forces, which exercise frequently and regularly, typically at least once per month along with one two-week period each year. Neither the German Bundeswehr nor the Italian Army regularly calls up reserves for training and exercises. In France, reservists are theoretically required to train at least 10 days per year. However, even when some units are called up for longer periods than this, it does not mean that any training for large-scale combat operations takes place. Rather, reservists could be called up to help protect military installations or patrol streets, with little to no time spent on improving combat skills. In Spain, reservists serve a maximum of seven days per year, although these seven days can be stretched out over a period of three years depending on the unit and service branch. In Britain, depending on the service branch and one’s specialization, annual training averages 27 days. In Poland, the reserves making up the Territorial Defence Forces are called up for one weekend each month, in addition to a two-week period every year, although the quality of training in these units can vary widely.
Beyond limited training time, another issue is the limited size and scope of exercises at both national and NATO levels, especially for European ground forces. Full brigade-size exercises involving reserve units are the exception, not the rule—although this is gradually changing. Larger exercises at the division or corps-level are practically nonexistent outside command post exercises, where staff officers simulate large-scale operations on maps and computers with no actual troops in the field. Reservists, except for those of the exercise’s host country, are generally also not included in large numbers in NATO exercises. The absence of large-scale training exercises for high-intensity combat is a major problem across all European NATO militaries. As one analyst put it: “Without being able to physically practice the co-ordination required for large-scale maneuvers, and experience the friction of war, our understanding of warfare is becoming increasingly theoretical, without the practical grounding necessary to test our doctrine.” Reinstating conscription might help raise the number of reservists, but it would not address these training deficits.
What needs to be done?
First, the size of reserve forces across European NATO militaries will need to undergo structural reorganization to be able to increase in size. Reserves should no longer primarily be used as piecemeal to plug gaps and fill troop shortages in active-duty forces but be more actively integrated and more uniformly trained to support high-intensity combat operations. This is the basic prerequisite for reserves to be capable of replacing active-duty personnel put out of action in a worst-case scenario. One way to do this would be to create more hybrid units consisting of active and reserve soldiers in addition to pure reserve units. When it comes to the manpower issue, one way to address it is to require all active-duty troops to serve in the reserves for a few years once their contracts are up. Some countries, such as France, are already looking into doubling the size of their reserve and making such reforms. Poland is also in the process of expanding its reserve force, the Territorial Defence Forces, but with mixed results thus far. And while there have been repeated calls in Germany to reform the reserves, including a new strategy announced in 2019, very little has changed.
Second, the scale, scope, frequency, and length of military exercises will have to increase. European NATO militaries will need to introduce more rigorous training schedules modeled on the U.S. reserve system and National Guard. Today’s situation—where there is perhaps one mandatory exercise every other year, every five years, or never at all—is clearly not sufficient to maintain military proficiency. At the same time, exercises need to become larger and more complex. The war in Ukraine has shown that large-scale conventional military operations are difficult to execute and so prone to friction that they cannot be adequately simulated in a synthetic training environment or tabletop exercise. France will be one of the first European countries to hold such a large-scale, divisional-level military exercise: Exercise Orion, involving around 10,000 troops, is scheduled for this spring and will include reservists. Poland plans to call up 200,000 inactive reservists for various training exercises. Other countries need to follow suit. These exercises, above all, need to hone skills in combined arms operations—a deadly game of rock, paper, scissors in which the “strengths of one platform or weapon systems supplements the strengths and weaknesses of another,” as I’ve written elsewhere. Proficiency in combined arms operations can help reduce casualties. One reason why both Russia and Ukraine have suffered so tremendously is because neither military has been capable of executing such combined arms operations effectively at scale.
Finally, to facilitate quick force generation for a high-intensity war in Europe, technology will become an ever more important part of the solution over the coming years and decades. In particular, the proliferation and integration of crewed and uncrewed ground and air systems as envisioned in, for example, the German-French-Italian Main Ground Combat System or the German-French-Spanish Future Combat Air System, could help substitute soldiers with uncrewed systems, act as force multipliers, and take over more dangerous missions in a high-intensity conflict. That will help reduce casualties. Technology, however, will not be a panacea. Organizational, structural, and doctrinal reforms will need to happen as well.
Conscription will not be the solution to help Europe’s leading militaries regenerate combat power in a future state-on-state war. Not only would it be financially draining, but it would also require a major restructuring that would leave these forces vulnerable for some years to come. Rather, reforming and expanding the reserve system could be financially less burdensome, politically easier to implement, and militarily more effective. Reforming the reserve would help increase European NATO members’ staying power in any future high-intensity war against another major military power. And according to the logic of deterrence, it would help reduce the chances of military conflict in the first place.