In 2014, when Russian forces entered the Crimean Peninsula, they faced remarkably little resistance. The Ukrainian military was weak, poorly trained, and corrupt. That was the Ukrainian military Russian President Vladimir Putin expected to encounter when he invaded the country again in February 2022. Assuming that the Ukrainian military would not put up much of a fight, Russia opted for a multipronged attack advancing from numerous locations in Russia, Belarus, and previously occupied Ukrainian territory. By the time it became clear that the multipronged invasion would not achieve the swift surrender that the Kremlin had expected, Russias forces were dispersed across a vast country and, in many cases, running critically short of supplies.

As Putin discovered, Ukraines military has undergone a radical transformation over the past eight years, thanks to intensive reorganization and reform efforts and billions of dollars in Western security assistance. In January 2022, the Congressional Research Service reported that the Ukrainian army had grown from about 6,000 combat-ready troops in 2014 to nearly 150,000 troops, a number that has been climbing higher since the Russian invasion, as Ukrainians from all walks of life have volunteered for military service.

The Ukrainian military has also vastly upgraded its equipment, thanks to a massive influx of Western military aid. Since 2014, the United States has provided more than $6.1 billion in security assistance to Kyiv, including more than $3.4 billion since the war began on February 24. In the weeks since the Russian invasion, the list of military equipment that Ukraine has received from the United States alone includes nearly 6,000 Javelin anti-armor systems, 1,400 Stinger missiles, 16 Mi-17 helicopters, and 90 155mm howitzer artillery systems, along with some 184,000 rounds of artillery.

In addition to hardware, Ukrainian troops have benefited from years of NATO and U.S. training. As a result of these cooperation efforts, the Ukrainian Special Operations Forces—which was first established in December 2015—now boasts seven special operations regiments, trained by the U.S. Special Operations Command Europe and capable of disrupting Russian operations, allegedly even in enemy territory. The Ukrainian military has also adopted a more sophisticated command-and-control system and created a professional noncommissioned officer corps modeled on that of the United States. Finally, although the full extent of this cooperation is unknown, the Ukrainians are receiving extensive, action-ready intelligence from the United States and NATO allies to support their defense against the Russians.

The Ukrainians have another advantage: because they are fighting an existential battle for the continued independence of their country, they are highly motivated and unified. Morale is a force multiplier. Beyond their willingness to fight, the Ukrainians are also demonstrating an impressive ability to deploy a particular style of warfare: asymmetric, insurgency-style tactics that even advanced conventional military forces of great powers have historically struggled to counter. This successful strategy blunted Russias attacks on Kyiv and other major cities.

As the war in Ukraine continues into its third month, one thing that became clear on its third day still holds true: that the Kremlin has severely overestimated the Russian military’s capabilities and deeply underestimated the skill and resolve of the Ukrainians. But the wars focus has now shifted to eastern Ukraine—and the open terrain of that part of the country calls for a different approach. If the Ukrainian military is to win in the Donbas, it must fight a more conventional war in a less favorable operational environment. What got the Ukrainians here may not help them there.

UNCONVENTIONAL TACTICS

Despite expectations to the contrary, the Ukrainian military has not collapsed, and the war against Russia has not devolved into an insurgency. This fate was avoided in no small part because Ukraines armed forces have adopted unconventional tactics. While conventional militaries generally have the advantage in numbers and firepower, insurgency tactics allow a smaller force to compensate with flexibility, mobility, and local knowledge.

Deciding not to engage the enemy in open terrain, where Russia’s advantage in numbers and heavy weapons could prove overwhelming, the Ukrainian forces fell back to the cities, where even the best-equipped invaders face poor odds. As Russian troops tried to push toward Kyiv and other major cities, Ukrainians took advantage of the Russians’ largely undefended supply lines and their inexplicable habit of moving tanks and other military vehicles onto open roads without using dismounted infantry troops to detect potential ambushes. Operating in smaller, more mobile units, Ukrainian infantry ambushed Russian tanks and armored personnel carriers. Armed with portable antitank weapons supplied by the United Kingdom and the United States, they destroyed and captured Russian equipment and halted Russias advance. As a bonus, inflicting such damage on Russias forces through ambushes and hit-and-run tactics had the psychological effect of humiliating the supposedly superior Russian military.

Facing an existential fight for their independence, Ukrainians are highly motivated. Morale is a force multiplier.

Even territorial defense battalions, which are largely made up of volunteers with little prior combat experience, have used guerilla-style tactics effectively. Consider an episode reported by Ukraines territorial defense forces in early March: an untrained 20-year-old recruit with a handheld grenade launcher stopped the lead tank in a Russian column on the outskirts of Kyiv before calling in the regular Ukrainian armed forces to destroy the rest of the column. These territorial defense battalions have served as the first line of defense in some areas, taking quick action before conventional troops could mobilize. According to interviews with local authorities reported in the Ukrainian media, when Russian troops first entered the city of Sumy, in northeast Ukraine, in late February, they were repelled by territorial defense units and bands of civilians using grenades, small arms, and Molotov cocktails. These actions bought time for the Ukrainian military to deploy heavier artillery, drones, and additional forces to defend the city, even as the surrounding area fell under Russian occupation.

Ukrainian defenders’ ability to communicate effectively with one another and with local populations has been crucial to their success. Ukrainian civilians and territorial defense units have used laptops, smartphones, and even a Telegram chatbot to keep one another and the military informed about Russian movements. In late February, residents’ tips allowed Ukraine’s armed forces to destroy over 200 units of Russian military equipment in the Poltava region. Civilian volunteers have also provided Ukrainian forces with food, clothes, armored vests, medical equipment, and night-vision devices.

In Mariupol, Ukrainian forces failed to repel the Russian invasion but nonetheless employed urban defense tactics to deny the Russians a much-desired victory. For over two months, the Russians have used heavy artillery and rocket fire, air attacks, and constant bombardment of civilian structures and infrastructure to take this strategically important port city. Even so, the stiff Ukrainian resistance forced the Russians to sacrifice many troops. According to a British intelligence update, the urban battle has exhausted the Russian forces and decreased their combat effectiveness. Despite the renewed Russian attempts to take over the last stronghold of the Ukrainian resistance in the city’s Azovstal Steel Plant, the images of Ukrainian defenders holding their own against Russian attacks on Mariupol continue to play a vital role in the information war, exposing the brutality and destruction caused by Russia and rallying Western support for Ukraine.

THE WAR SHIFTS EAST

After announcing its decision to shift offensive combat operations to the Donbas region last month, Russia has withdrawn its forces from around Kyiv and Chernihiv, a city 100 miles north of the capital. The brunt of the fighting now seems concentrated in Ukraine’s east. This theater of operations offers very different conditions from those faced earlier in the campaign and will require both Russians and Ukrainians to adjust their strategies.

To win in the Donbas, the Russians must quickly pivot away from the failed strategy of trying to seize Kyiv that got them bogged down in urban centers spanning the north, east, and south of Ukraine. Instead, they must implement a plan that takes advantage of the more favorable terrain in the east. The open spaces and sprawling plains of the Donbas region present the kind of operational environment that large, conventional militaries such as Russia’s prefer. This terrain could allow Russia to amass forces, maneuver large artillery pieces such as mortars and howitzers, and advance armored assaults to surround and cut off Ukrainian troops in the east. The Russians could also employ their air force more extensively. The proximity to Russian and Russian-held territory, meanwhile, could help moderate logistical challenges on the ground.

But Russian forces may be too depleted and demoralized to fully capitalize on the operational advantages of the war’s new geography. Russia’s tank and motorized rifle units and its elite Spetsnaz and airborne forces, which would be the collective backbone of the fight in Donbas, have already suffered catastrophic losses and are particularly hard to replace. Although Russia has appointed an overall commander for the operation to help with coordination, and even sent the chief of the general staff of the Russian military, General Valery Gerasimov, to visit the frontlines, the more fundamental logistical, communications, and command-and-control problems are not easily solved. Moreover, pressure to demonstrate objectives met in time for May 9, when Russia celebrates victory over Nazi Germany, could force mistakes.

The Ukrainians face almost the opposite challenge. To win in Donbas, they will likely have to shift to a more conventional fight on open ground, where they may be more vulnerable. The terrain in the east does not offer the cover allowed by forests and urban areas, making it more difficult for Ukrainian forces to conduct the insurgency-style attacks that worked so well in the first stage of the war. In this conventional style of warfare, the Ukrainians need more tanks, artillery, and rockets to conduct a large-scale counteroffensive. But getting the weapons and equipment arriving from the Western countries to the frontlines could take more time and require covering more ground than it did before, potentially leaving the supply lines vulnerable to Russian attacks.

Numbers also matter for the Ukrainian side. A small, well-equipped, highly motivated force could defend a city against a much larger offensive force and even win. In open terrain, especially if the Ukrainians want to move from a defensive posture, regain lost territory, and expel Russian soldiers from the Donbas region, they will need serious reinforcements. There is limited information about how many Ukrainians have died in battle so far. Given the intensity of the fight and the scale of Russian losses, they are likely to be far higher than official Ukrainian estimates.

The Ukrainians have proved to be more flexible than the Russians. The diffuse command structure and the autonomy that allowed for each operational command to coordinate operations best suited to local conditions should continue to work to Ukraine’s advantage—and the forces deployed in the Donbas are some of the countrys best and most experienced, having spent the last eight years fighting the Russians and Russian-backed separatists. Although likely more dangerous in open terrain, ambushes and hit-and-run attacks against Russian supply lines can still cause damage. Morale remains high, and Western countries seem committed to supplying military aid and intelligence support. While nothing is guaranteed, the Ukrainians do have some of the main pieces in place to keep their momentum going and to adapt to the new battleground in the Donbas.

AN UNCERTAIN FUTURE

Attempting to predict the trajectory of this war has proved an exercise in futility. And while hindsight is always 20/20, the odds of a quick, decisive victory for Russia were never good. Not for an offensive campaign that presumed to take a city the size of Kyiv without a hard fight. Certainly not once the offensive splintered across multiple urban fronts. The history of urban warfare, after all, is marked by bitter battles of attrition. The war in the Donbas is shaping up to be a largely conventional fight, fought in open terrain between two sides that are relatively well matched in numbers and equipment. Although this new operational environment in the east is forcing both Russia and Ukraine to adjust their strategies, the power parity, in this case, does not favor a quick victory.

Nor is a rapid, decisive result likely once politics are taken into account. The Ukrainians are empowered by their successful repelling of Russia’s offensive on Kyiv and outraged by the evidence of heinous war crimes against ordinary civilians. They have little incentive to accept a cease-fire that eats at their territory. At the same time, Putin is unlikely to settle for a stalemated fight with limited control beyond the already disputed parts of eastern Ukraine as the outcome of a war that promised so much more and has already cost the Russian military so dearly. Recent expert assessments suggest that Russia may be preparing diplomatically, militarily, and economically for a protracted conflict. The fight in the Donbas is therefore likely to be brutal, but it will not be swift, and it may not be decisive.

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