It has been six months since Russia invaded Ukraine, and it’s not obvious who’s “winning” the war.

The first stage of the Russian attack in February, a lightning thrust aimed at seizing Kyiv and decapitating the Ukrainian government, was a swift and humiliating failure. Stiff Ukrainian resistance forced the Russians to withdraw to the eastern part of the country, where their ambitions narrowed in the short term to a conquest of the Donbas region (much of which had already been controlled by Russian-backed separatists since 2014).

In the Donbas offensive, which began in late April, the two sides have been locked in an artillery duel — less rapid troop advancement and more firing shells and rockets from afar. This played to Russia’s primary strength, a numerically superior artillery corps, and led to high Ukrainian casualties and slow but steady Russian gains in the spring and early summer.

More recently, however, the momentum has started to swing back to the Ukrainian side. Western military aid — most notably an American rocket artillery system called HIMARS — has helped level the artillery playing field and wreaked havoc on Russian supply lines. Today, experts aren’t asking whether Ukraine will launch a counteroffensive aimed at retaking Russian-held territory, but when it will start and where it will focus.

Whether this means Ukraine is now “winning,” however, is a somewhat more complicated question to answer. We don’t know that the upcoming counteroffensive is likely to succeed; it depends on factors about which we have limited evidence, like Ukraine’s ability to conduct so-called “combined arms” offensive operations (ones that employ multiple components of military power simultaneously to accomplish a particular goal). Some important quantitative metrics, like the size of their respective ammunition stockpiles, are hard to estimate based on publicly available information. At this point, even leading experts on the conflict find it difficult to assess with real confidence who’s winning on the battlefield.

The broader strategic picture is less opaque — but only somewhat.

On one level, it’s been clear ever since Russia failed to take Kyiv that Russia was facing some kind of defeat. Nothing short of successfully seizing control of the Ukrainian state could justify the damage done to Russia’s military, economy, and international reputation. The invasion has already backfired on Russia, and its remaining battlefield efforts are focused on making the most out of a bad situation — to make sufficient gains that it could sell the war as a win to its population and the world.

But just because the war has been bad for Russia doesn’t mean that it’s a victory for Ukraine. The invaded nation has suffered grievous losses since the fighting began; a large swath of its east and south is currently occupied by Russia. Improving its postwar situation will almost certainly require more battlefield victories, ones that would leave Russia no choice but to give up many of its gains at the negotiating table.

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So six months in, we know quite a bit more about what things will look like after the war than we did when it started. But there’s still a lot to be determined, and neither side is showing signs of backing down. There’s almost certain to be a lot more fighting ahead.

How to assess who’s winning on the battlefield, and why Ukraine is poised to go on the offensive

Sometimes, progress in war can be approximately measured by territorial gains and losses. But in artillery duels like the current fighting in the Donbas, territorial changes are typically a lagging indicator rather than a leading one. So long as both sides maintain the ability to keep up the barrage, it’s hard for either one to make significant advances. Large changes in control typically happen after one side is exhausted — when they’ve lost so many troops, artillery pieces, and/or shells that they are forced to rapidly retreat.

“In a war of attrition forces are degraded gradually, but may then lose control suddenly, because they find themselves eventually placed in an untenable position,” says Michael Kofman, an expert on the Russian and Ukrainian militaries at the CNA think tank.

Instead of tracking territory, Kofman proposes a three-part test for assessing which side is winning:

1. Which side has the initiative, defined as “setting the pace of operations and forcing the other side to react to them.”
2. Which side is losing the war of attrition, defined as who is suffering greater losses in manpower and materiel.
3. Which side has a better capacity for sustainment, defined as “which side is better able to reconstitute their forces and replace their losses” in the “medium-to-long term.”

For most of the conflict, Russia has had the initiative. Moscow launched the invasion and then forced Ukraine to mount desperate defenses of its major cities, including the capital Kyiv. Even after this assault failed, Russia was able to set the terms for the next part of the conflict — launching a new offensive in the Donbas region that forced a reactive Ukrainian defense.

But in the past few weeks, Ukraine has started to take the initiative. A key factor has been Ukraine’s ability to target the Russian army’s supply chain — what Simon Schlegel, the International Crisis Group’s senior analyst for Ukraine, describes as its “Achilles’ heel.”

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In the past few weeks, Ukraine has used its artillery systems to hit Russian railways, infrastructure, and ammunition dumps. The Russians have been making significant use of truck convoys to bring supplies to the front, but those are less efficient and easy for the Ukrainians to target while being offloaded.

HIMARS, an American-made rocket launcher system mounted on a truck, has been a central part of the strategy. HIMARS rockets are precise, capable of destroying Russian facilities at range. They’re also fairly easy to move — the acronym HIMARS stands for “high mobility artillery rocket system” — which makes it hard for Russian counter-battery forces to target. So far, Ukraine has yet to lose a single HIMARS launcher to enemy fire. And HIMARS is one of several advanced systems given to Ukraine as part of the roughly $10 billion in military aid provided by the Biden administration, supplemented by billions more from European nations.

Ukraine has also demonstrated an ability to strike deep into Russian-held territory. Since early August, Ukrainian aircraft and partisans have hit military targets in Crimea, the southern Ukrainian peninsula seized by Russia back in 2014, including an airbase and the headquarters of the Russian Black Sea Fleet. These strikes haven’t transformed the conflict, but they have created a sense of insecurity on the side and contributed to a sense that Ukraine is setting the terms of the conflict.

There appears to be a window open for Ukraine to launch its own counteroffensive: to try to take advantage of Russia’s weakness and retake vital territory. The attack appears likely to come in southern Ukraine, but it’s not obvious where.

Institute for the Study of War

The most bandied-about target is Kherson, the only Ukrainian provincial capital taken by Russian forces. Liberating Kherson would be a significant victory for Ukrainians, a potent symbol that would shore up Ukrainian morale and encourage its Western patrons to keep backing what looks like the winning horse.

A bolder option would be a push south down from Zaporizhzhia, a city just on the east side of the Dnipro River. In this plan, Ukrainian forces would primarily aim to sever the lines connecting Crimea to Russian holdings in the Donbas — a move that could do significant damage to Russia’s ability to maintain these holdings, but that also risks Ukrainian forces becoming enveloped by Russians positioned on either side of their advance.

Whatever the Ukrainians attempt, it very well may not succeed.

Attacking is generally harder than defending; the military rule of thumb is that attackers need a three-to-one troop advantage in order to have a chance of success. Ukraine has a manpower advantage despite its smaller population, as the Kremlin has proven unwilling to go to a total war footing and call up its reserves, but has suffered heavy losses of its own in the past six months. (Ukraine’s top general recently said about 9,000 of his country’s soldiers have been killed, but the actual number is probably significantly higher.) It’s far from clear how much of an advantage they’ll have in any southern offensive.

Moreover, the kind of offensive Ukraine seems poised to launch depends heavily on Ukraine’s “combined arms” capacity. Combined arms operations are complex, requiring that infantry, armor, artillery, and airpower all coordinate effectively to cover each other’s vulnerabilities and enable movement through enemy-controlled territory. So far, the Ukrainians have not yet mounted a significant combined arms offensive in the current war, and we have little insight into their capacity for doing so.

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Any such attack will be costly, leading to significant Ukrainian attrition. While territorial success might encourage the West to increase its support for Ukraine, poor battlefield performance could undermine it — significantly weakening Ukraine’s capacity for sustainment across the board.

So, yes, things are looking up for Ukraine on the battlefield right now. But how long that will continue is far from clear.

Russia probably can’t win — but that doesn’t mean Ukraine will

In war, battlefield victories are not an end in themselves; they are a means to attaining particular political goals.

In some cases, the relationship between battlefield and political objectives is straightforward. One side defeats the other completely, conquering their territory or forcing an unconditional surrender. Some of history’s most famous conflicts, including the US Civil War and World War II, fit this model. But these conflicts are the exception rather than the rule.

“The World War II settlement [in which] the losers lose everything is relatively uncommon in history,” says Emma Ashford, a resident senior fellow at the Atlantic Council.

The current war in Ukraine, according to Ashford, is not likely to buck the trend. A total Russian victory, conquering Ukraine, is at this point clearly out of reach. Ukraine’s maximalist aim, pushing Russian forces out of its internationally recognized territory entirely, does not currently appear to be within its capacity.

As a result, it is overwhelmingly likely that this war will be resolved at the negotiating table: through Kyiv and Moscow agreeing to some kind of ceasefire or treaty in which neither side gets all of what it wants.

These negotiations will be fundamentally shaped by battlefield outcomes: If one side has a significant advantage in the field, they have more leverage to extract favorable terms from the other. But it will also be shaped by other factors, including public opinion in Ukraine and Russia, economic damage caused by continued fighting (in Ukraine) and Western sanctions (in Russia), and the capacity for Western states to continue resupplying Ukraine from their own stockpiles and factories. So if “winning,” in a strategic sense, is defined as attaining a more favorable political outcome, battlefield victories do matter — but they’re not the only thing that does.

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Right now, any kind of negotiated settlement seems very far away. Peace talks held early in the conflict proved abortive, and while talks have produced some small agreements between the two countries, the leadership on both sides seems convinced that they can still improve their situation on the battlefield. So long as this will to fight remains, it’s extremely difficult to speculate about the specifics of a peace settlement, let alone whether it would be more favorable to one side or the other.

That said, there is one big-picture conclusion that’s already clear: This war is a strategic disaster for Russia.

At the outset, the Russian war plan depended on speed: a rapid march to topple the Ukrainian government that would end the war before it really got started. Once Russia seized the bulk of the country, it would present it to the world as a fait accompli — one that Washington and Brussels would be unwilling to seriously contest. Russia would get what it wanted — effective sovereignty over Ukraine — at little cost.

But this plan was badly flawed, depending as it did on wildly unrealistic assumptions about Ukrainian military weakness. Once it failed, and Russia became bogged down in a protracted war without any decisive end, the costs in manpower and materiel began to mount — as did the damage to Russia’s economy and international reputation. Russia could still meaningfully improve its situation on the battlefield, by expanding its territorial holdings in Ukraine and potentially forcing Kyiv to formally cede some of it to Russia, but it’s nearly impossible that Russia could realistically seize enough territory to make its decision to invade pass any rational cost-benefit analysis.

“Russia clearly failed to achieve its early war aims,” Ashford says. “They probably lost strategically already.”

But if Russia has “lost” in that most basic sense, it doesn’t follow that Ukraine has already won.

True, Ukraine has repulsed Russia’s initial invasion attempt; its survival as a sovereign entity is no longer in immediate jeopardy. But the long-term damage from the invasion — the mass death and displacement of its citizens, the destruction of its cities, the demolition of its domestic manufacturing capacity, the torching of its agricultural sector — is severe. For Ukraine to secure a stable footing for itself in the long run, it would need to extract some significant concessions from Russia and an extensive international commitment to support its postwar reconstruction efforts.

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Ukraine’s future, then, depends on the success of its war effort. Russia, by contrast, is fighting to minimize its losses — to salvage something from the geopolitical wreckage wrought by the decision to invade in the first place. Both sides believe they can improve their ultimate outcomes on these metrics on the battlefield; neither shows any interest in suing for peace.

As a result, the length of the most devastating European war since 1945 is less likely to be measured in months than in years.