In the months since Russia's blitzkrieg attack from the north and east, which was met with a stronger-than-expected resistance from the outmanned and outgunned Ukrainians, the evolving conflict has become more of a "static war" with no clear winners, according to ABC News contributor retired Col. Steve Ganyard.
"At this stage, both countries, both Ukraine and Russia, seem to be losing," Ganyard said. "And now the fight is obviously who can lose first and who will have to lose last."
It's impossible to predict how much longer the war will last -- it could be months or even years, Ganyard said.
"This is a war that's unfolding at this point very, very slowly," he said. "Neither side has the ability to conduct significant offensive operations."
How long the fighting continues until one side "loses first" will likely depend on a few factors.
For Russia, getting troops on the ground to maintain the territory it's taken is one, as recruiting personnel has been a challenge, Ganyard said.
The Russian military hasn't given an official update on casualties since late March, when it reported around 1,350. One U.S. Department of Defense official estimated earlier this month that at least 70,000 Russians have been killed or wounded since the start of the war.
"There's a lot of fog in war, but, you know, I think it's safe to suggest that the Russians have probably taken 70 or 80,000 casualties in less than six months," Colin Kahl, the undersecretary for defense for policy at the Department of Defense, told reporters.
Russian President Vladimir Putin has a "very difficult chore" to recruit qualified military personnel to fight in Ukraine, Ganyard said.
"The Russians are basically recruiting out of prisons at this point," he said. "They have not mobilized the whole nation."
The number of Ukrainian soldiers killed since Feb. 24 is classified, but deputy minister of defense Hanna Maliar has said there are "thousands." There have also been thousands of civilian casualties; the Office of the United Nations High Commissioner for Human Rights estimates that over 5,500 have been killed and over 7,600 injured in Ukraine since Feb. 24.
For Ukraine, continued support from the West will be key, Ganyard said, including supplies of precision weapons such as the long-range High Mobility Artillery Rocket Systems, or HIMARs, which Ukrainian forces have used to wear down Russians in rear areas.
"The ability for the Ukrainians to target very precise locations -- command posts, supply depots -- this allows the Ukrainians to begin to attrite and wear down the Russians in their rear areas, take away the supplies that they're using to conduct this war," Ganyard said.
This development is "unprecedented" so far in the conflict, he said.
"Up to this point, the war had been basically a slugfest -- artillery against artillery," he said. "But now that the Ukrainians have this long-range capability where they can hit very precise coordinates, it gives them an offensive advantage."
Though as the conflict continues, there is a risk for Ukraine that Western support could wane as the impacts of the war, such as from energy supplies in Europe, are felt in the months ahead, he said.
How much more of a beating their contracted economies can withstand will be a factor for both countries, Ganyard said.
"As we see both economies get drawn down, as we see both militaries being punished and diminished, it's going to be a question of who can survive and who can lose last," he said.
Morale also continues to be crucial, with Ukraine buoyed by its offensive advantage while Russia looks to hold ground in hostile territory, he said.
For Kahl, "Ukrainian morale and will to fight is unquestioned and much higher, I think, than the average morale and will to fight on the Russian side," he told reporters. "I think that gives the Ukrainians a significant advantage."
With those factors in consideration, there are several ways the conflict could potentially play out:
Russia holds ground in Donbas, Ukraine relinquishes territory
In a "best-case scenario" for Russia, its troops will continue to gain incrementally in the Donbas and hold their ground against Ukrainian forces, Ganyard said. If Ukraine doesn't have the arsenal to push back or can't hold out amid a downhill economy, that could put them in a position to sue for peace, he said.
"Where the Russians are pushing in from the east toward the west, that is the bread basket of Ukraine," Ganyard said. "That is where not only most of the industry is, but it's where most of the agriculture, very rich agricultural area, all of that gets transported down the Dnipro River.
"If Russia would be able to hang on to that, it would almost cut Ukraine in half, and certainly cut the Ukrainian economy by more than half," he continued.
Ukraine regains territory in the Donbas, Russia cuts its losses
If Ukraine manages to recapture some of the territory in the Donbas claimed by Russian forces since the invasion started, that could pressure Putin to end the invasion to stave off further embarrassment, Ganyard said.
"If he began to lose, if he began to take even heavier losses, if the Ukrainians were able to recapture parts of Ukraine that the Russians have taken, at some point Putin may decide to cut his losses and declare victory and take whatever's left on the table in terms of the territory that he's taken thus far," Ganyard said.
Ukraine regains territory in the Donbas, Russia escalates
Alternately, Putin may push back against the political embarrassment of losing territory it had gained since the start of the invasion, Ganyard said.
"The more gains that the Ukrainians make, it's actually going to make the whole situation more dangerous because Putin may react in a way that escalates to de-escalate," Ganyard said. "We've heard that term in the past, and usually that refers to the use of tactical battlefield nuclear weapons.
"The danger here is if the Ukrainians continue to do better, what does Putin do to save himself to save his beloved, domestic political position?" he continued. "Does he do something that would shock the whole world and try to scare the Ukrainians into an early surrender?"
Ukraine pushes south, putting pressure on Putin
Kherson, a port city on the north of the Crimean Peninsula, was the first major city to fall after Russia launched its invasion. The city is key to Ukraine for its access to the Black Sea and ability to move goods. If Ukraine manages to make ground and pushes past Kherson and threatens Russia-annexed Crimea, that could give Ukraine a negotiating advantage, Ganyard said.
"[Ukrainian President Volodymyr] Zelenskyy will continue to try to threaten Crimea to be able to pressure Putin," he said.
That could look like threatening to turn off the freshwater supplies into Crimea, he said.
"There's all sorts of unknowns here about what happens," Ganyard said. "As they go into the fall and into the winter, there may be some movement in terms of the negotiations. But at this point, neither side can afford to give up the kinds of military actions that we see on the ground to this point."