It has been a little over three weeks since Russia initially invaded Ukraine. And by most accounts, the Russian war effort has been a disaster.

The initial Russian invasion plan, a lightning march aimed at conquering Kyiv, collapsed within days. Since then, the Russians have adjusted to a more gradual advance backed by heavy artillery fire, an approach that has allowed them to make some noticeable territorial gains.

But these advances appear to have been halted, at least temporarily. On Thursday, the UK Defense Intelligence Agency assessed that Russia’s offensive “has largely stalled on all fronts,” a judgment echoed by open source analysts tracking developments on the ground. The Wall Street Journal reported on Wednesday that Ukrainian forces have even managed to mount a counteroffensive around Kyiv.

Russian casualties have been horrifically high. It’s hard to get accurate information in a war zone, but one of the more authoritative estimates of Russian war dead — from the US Defense Department — finds that over 7,000 Russian soldiers have been killed in the first three weeks of fighting, a figure about three times as large as the total US service members dead in all 20 years of fighting in Afghanistan.

“We’re seeing a country militarily implode,” says Robert Farley, a professor at the University of Kentucky who studies air power.

This is not how the war was supposed to go. On virtually any quantifiable metric of military strength, from defense spending to the size of the respective air forces, Russia’s forces vastly outnumber and outgun Ukraine’s. In early February, Chairman of the Joint Chiefs Mark Milley told members of Congress that Kyiv could fall within 72 hours of a Russian invasion.

But Russia’s military has proven more incompetent, and Ukraine’s more capable, than nearly anyone anticipated.

Sergei Supinsky/AFP via Getty Images

“Having spent a chunk of my professional career [working] with the Ukrainians: Nobody, myself included and themselves included, had all that high an estimation of their military capacity,” says Olga Oliker, the program director for Europe and Central Asia at the International Crisis Group.

There are many reasons things have turned out this way. Generally speaking, it appears that pre-war analyses overrated Russia’s hardware advantage and underrated less tangible factors — including logistical capacity and the morale of the front-line combat troops on both sides.

Morale in particular “is a very significant factor in Russian combat effectiveness, and one that’s being ignored by many military observers,” argues Michael Kofman, director of Russia studies at the CNA think tank.

All that said, it is still far too early to conclude that Ukraine is going to win the war. Ukrainians have suffered significant losses, too; Russia’s numerical and technological advantages remain and could yet prove decisive, allowing the Russians to besiege Ukraine’s major cities and starve them into submission.

But right now, based on the publicly available evidence we have, the momentum is clearly going the other way. An unqualified Russian victory, which once seemed almost inevitable, is looking increasingly less likely.

Russia’s gains have been real — but are stalling out

On paper, Russia’s military vastly outstrips Ukraine’s. Russia spends over 10 times as much on defense annually as Ukraine; the Russian military has a little under three times as much artillery as Ukraine and roughly 10 times as many fixed-wing aircraft.

Given this disparity, Russia was bound to be able to make some inroads into Ukrainian territory. And as you can see on the following map from the Institute for the Study of War (ISW), Russia had seized control of notable chunks of Ukrainian territory by March 9 — especially in the south, where it controls the cities of Melitopol and Kherson:

Institute for the Study of War

But these advances were not necessarily the sole result of Russian battlefield supremacy. Ukraine, Kofman explains, made the tactical decision to trade “space for time”: to withdraw strategically rather than fight for every inch of Ukrainian land, fighting the Russians on the territory and at the time of their choosing.

As the fighting continued, the nature of the Ukrainian choice became clearer. Instead of getting into pitched large-scale battles with Russians on open terrain, where Russia’s numerical advantages would prove decisive, the Ukrainians instead decided to engage in a series of smaller-scale clashes.

Ukrainian forces have bogged down Russian units in towns and smaller cities; street-to-street combat favors defenders who can use their superior knowledge of the city’s geography to hide and conduct ambushes. They have attacked isolated and exposed Russian units traveling on open roads, which make for easy targets. They have repeatedly raided poorly protected supply lines with an eye toward denying Russians necessary materials like fuel.

A recent Washington Post account of a battle near the Kyiv suburb of Brovary, based on Ukrainian military videos and interviews with witnesses, paints a clear picture of how this has played out:

A column of tanks moved down a main highway toward the town of Brovary. As they passed a cluster of houses, the Ukrainian forces saw an opportunity. They pummeled the convoy with artillery shells and antitank missiles, destroying or disabling several tanks and armored personnel carriers. Russian soldiers fled their vehicles and ran into the woods, according to videos posted on social media by Ukraine’s military. One tank slowly rolled to a halt, engulfed in flames.

The Ukrainian defensive strategy has not fully thrown Russia’s advance back, but it has slowed it to a near halt. ISW’s updated March 17 map shows that Russian forces have barely moved forward from their positions about a week earlier — a reflection of Ukrainian success:

Institute for the Study of War

Again, the Russian advancement mostly came in the south, where they continue to besiege the port city of Mariupol. Their current aim appears to be to do the same to Kyiv in the north, cutting it off from food and water and bombarding it with artillery.

In theory, this is something their vastly superior military forces should be able to accomplish. In practice, the Ukrainians have successfully stopped Russia from encircling their capital and may even be able to push Russian forces back.

And Russian casualties are taking their toll on the invasion. A recent US intelligence assessment found that Russia had lost over 10 percent of its initial invasion force due to a combination of factors like battlefield deaths, injuries, capture, illness, and desertion. According to Phillips O’Brien, a professor of strategic studies at the University of St. Andrews, this is a very ominous sign for the future of its campaign.

“Once they get below 75% their overall effectiveness should plummet,” he writes. “If the Russians don’t send fresh well-trained troops (and this will not be mercenaries or people impressed off the streets in Crimea) very soon, their whole strategy seems pointless.”

What is wrong with the Russian military?

To understand why the war has gone in such a surprising direction, we can first look at some of the Russian side’s problems. They started with Putin himself.

The initial invasion plan was reportedly put together in secret by a handful of his top military and intelligence advisers; it reflected the Russian strongman’s seemingly sincere belief that Ukraine was a fake country and they could achieve regime change with limited resistance.

“He actually really thought this would be a ‘special military operation’: They would be done in a few days, and it wouldn’t be a real war,” Kofman says.

Fadel Senna/AFP via Getty Images

You can see this assumption at work in the structure of the early offensive. Instead of a methodical advance characterized by “combined arms” — the use of multiple forms of military power, like infantry and artillery, in mutually supportive fashion — Russian tanks and elite paratroopers were sent pell-mell toward Kyiv with little support. This kind of rapid advance might have worked if it had faced token resistance, but it opened up Russian forces to devastating Ukrainian counterattacks.

Once Putin’s strategy failed in the first few days of fighting, Russian generals had to develop a new one on the fly. What they came up with — massive artillery bombardments and attempts to encircle and besiege Ukraine’s major cities — was more effective (and more brutal). But the initial Russian failures gave Ukraine crucial time to entrench and receive external supplies from NATO forces, stiffening their defenses.

Even after this strategic shift, Russian forces have continued to suffer from a series of problems that have kneecapped their ability to execute the plan.

“If the point is just to wreak havoc, then they’re doing fine. But if the point is to wreak havoc and thus advance further — be able to hold more territory — they’re not doing fine,” Oliker tells me.

One of the biggest and most noticeable issues has been rickety logistics. The most famous images of this have been Russian armored vehicles parked on Ukrainian roads, seemingly out of gas and unable to advance any further. But on a whole range of issues, from secure communications to adequate tires, the Russian forces have proven to be underequipped and poorly supplied.

Part of the reason is a lack of adequate preparation. Per Kofman, the Russian military simply “wasn’t organized for this kind of war” — meaning, the conquest of Europe’s second-largest country by area.

Aris Messinis/AFP via Getty Images

Another big problem, experts say, is corruption in the Russian procurement system. Corruption in Russia is less a bug in its political system than a feature; one way that the Kremlin maintains the loyalty of its elite is by allowing them to profit off of government activity. Military procurement is no exception to this pattern of widespread corruption, and it has led to troops having substandard access to vital supplies.

“Ineffective control over fuel consumption in the Russian military actually long preceded the war in Ukraine and had historically created opportunities for embezzlement — that is why fuel is often called the Russian military’s ‘second currency,’” Polina Beliakova writes in Politico. “The quality of food and housing in the Russian military is reportedly worse than in its prisons, with unreasonably small meals and some carrying harmful Escherichia coli bacteria.”

Logistical problems also seem to be a factor in one of the war’s biggest and most important surprises: the shocking absence of Russia’s air force.

So far, Russia has struggled to establish air superiority despite massive numerical superiority. According to pre-invasion data from the International Institute for Strategic Studies, Russia’s aerospace forces include 1,172 fixed-wing aircraft; Ukraine has 124. Yet Ukraine’s planes are still flying and its air defenses mostly remain in place; as a result, the Ukrainian military has been able to use air power against the Russian attackers, including deploying Turkish-made TB2 drones against slow Russian armored columns to devastating effect.

According to Farley, the issues with Russia’s air force run even deeper than lack of maintenance and fuel: Russian pilots lack adequate experience with this kind of campaign and do not train very effectively, while the leadership seems afraid to risk jets over Ukrainian skies.

“There’s a big hangover from the 1990s and the early 2000s, when [Russia] literally didn’t have the money to pay for the gas to make the aircraft fly — so your pilots ended up not having many hours in the sky,” he explains. “Unlike the United States, which wages a massive air campaign every decade, the Russians really haven’t done stuff that require a lot of fixed-wing against any kind of prepared defense.”

Ukraine’s stiff resistance and the importance of morale

Perhaps the biggest single difference between the Ukrainian and Russian militaries, according to the experts I spoke with, has been morale: soldiers’ belief in their cause and willingness to fight for it.

Rodrigo Abd/AP

“It’s the one thing that could be completely decisive” in Ukraine’s favor, says Farley. “Armies do just decide to stop fighting.”

Morale is, by its nature, a tricky thing to assess. But according to Dartmouth political scientist Jason Lyall, whose recent book Divided Armies examines the role of morale on battlefield performance, you can see its effects in dispatches from the Ukrainian front.

“Russian morale was incredibly low BEFORE the war broke out. Brutal hazing in the military, second-class (or worse) status by its conscript soldiers, ethnic divisions, corruption, you name it: the Russian Army was not prepared to fight this war,” he explains via email. “High rates of abandoned or captured equipment, reports of sabotaged equipment, and large numbers of soldiers deserting (or simply camping out in the forest) are all products of low morale.”

Putin kept the Russian invasion plan a secret from everyone but his inner circle; before the invasion, Russian diplomats and propaganda outlets were mocking the West for suggesting it might happen. The result is a Russian force that has little sense of what they’re fighting for or why, waging war against a country with which they have religious, ethnic, historical, and potentially even familial ties. That’s a recipe for low morale.

By contrast, the Ukrainians are defending their homes and their families from an unprovoked invasion. They have a charismatic leader, Volodymyr Zelenskyy, who has made a personal stand in Kyiv. Stories of heroism and defiance — like Ukrainian soldiers responding to a surrender request by saying “Russian warship, go fuck yourself” — have bolstered the defenders’ resolve.

The Ukrainian morale advantage is making a difference on the battlefield.

“High morale empowers units to take risks, adopt unpredictable tactics, and to endure hardships even when outnumbered,” Lyall tells me. “High Ukrainian morale, fueled by Zelenskky’s remarkable leadership and personal courage, has improved Ukrainian cohesion and the ability of its forces to impose significant casualties on Russian forces.”

Ukrainian Presidency/Handout/Anadolu Agency via Getty Images

Lyall cautions that morale can shift with battlefield developments: A major Russian breakthrough in one area could cheer up their troops while dispiriting Ukrainians. And low-morale armies can win wars, though they typically do so in brutally ugly fashion — including mass slaughter of civilians, which appears to be a significant part of Putin’s current strategy.

But right now, morale appears to be one of the most important factors in explaining the difference between the two militaries’ performance. It could end up playing a major role in determining the entire course of the war.

What does victory for either side look like now?

War is unpredictable. Any number of things, ranging from Russian reinforcements to greater deployment of its air force to the fall of besieged Mariupol, could give the Russian offensive new life.

But even if Russia begins to perform better on the battlefield, its initial objective — “a Ukraine that becomes entirely subservient to Russia,” as Oliker puts it — is looking increasingly out of reach. The inability to swiftly topple Kyiv, together with the strong resistance and rising nationalist sentiment among Ukrainians, makes it hard to imagine Russia successfully installing its own government in Kyiv.

“No matter how much military firepower they pour into it, they are not going to be able to achieve regime change or some of their maximalist aims,” Kofman declares.

This does not mean the Russian campaign will prove to be a total failure. Depending on how the rest of the military campaign goes, it is possible to imagine them extracting significant political concessions from Zelenskyy in ongoing peace negotiations.

Fadel Senna/AFP via Getty Images

If more major cities like Kyiv, Kharkiv, and Odesa are put under the sort of horrible siege Mariupol is currently experiencing — starved and under constant artillery bombardment — the Russians will have a lot more negotiating leverage. They could use this to extract favorable terms, like Ukrainian recognition of Russia’s annexation of Crimea and a neutrality pledge not to join NATO or the European Union.

But if current military trends hold, it’s the Ukrainians who have the cards — and you can imagine a deal that looks similar on paper actually favoring them significantly. According to Ukraine’s Euromaidan Press and the Financial Times, the country’s negotiating team in peace talks with Russia envisions a very specific version of “neutrality”: one that precludes formal NATO membership but nonetheless commits Western powers to providing weapons and air defense if Ukraine is attacked. This would put Ukraine in a far closer security relationship to the West than it was before the war, when NATO membership was already functionally out of reach — a victory for Kyiv and defeat for Moscow.

It is hard to say how these talks will go, or if and when they will be successful. But the fact that a negotiated end to the war is looking more likely than total Russian victory reflects the success of Ukraine’s defense to date.

“Ukraine’s battle is really for time, an extent to which they can [degrade] Russian forces over time in order to steadily lead Russia to revise down their war aims. And we’ve already seen a change in Russian war aims over the course of the conflict,” Kofman says. “If the requirements of military success are the destruction of the Ukrainian capital and several other cities, the likelihood of achieving actual political aims is nil.”