The Ukraine war rages on without a clear end in sight. Here are 6 ways the conflict with Russia could play out

• One year on from Russia invading Ukraine, there does not appear to be a clear end in sight to the conflict.
• A military expert said Vladimir Putin's "in too deep" and is unlikely to withdraw without clear successes.

With Russia's war in Ukraine having begun one year ago, there is still no clear end to the carnage in sight. Tens of thousands of soldiers are dead or maimed, entire cities have been reduced to twisted piles of rubble, there have been allegations of torture and atrocities by Russian occupiers, and millions have become refugees.

While Russia has occupied swathes of territory in the south and east of the country, Ukraine has put up a stronger fight than anyone expected and often humiliated Russian President Vladimir Putin's invasion forces that, on paper, were meant to overwhelm Ukraine in days.

Not only have the Ukrainian defenders fended off a total conquest from Russia, they have also retaken parts of the country by launching well-organized, audacious counter-offensives in the east and south.

However, despite the battlefield defeats, Russia still has destructive military capabilities it can call upon, and it has launched missile and drone blitzes on Ukraine's energy infrastructure and launched a bloody assault on the city of Bakhmut.

While the largest war in Europe since 1945 seems to have entered an attritional phase, there are several ways the conflict could play out.

Cease-fire

If the fighting reaches a stalemate, there could be some negotiated, temporary cease-fire between Russia and Ukraine, according to Seth Jones, the director of the Center for Strategic and International Studies, or CSIS, International Security Program.

"That would probably not be an end, though, that would be the state of active warfare declining, at least temporarily, and it becomes something closer to a frozen conflict that can heat up or cool down depending on the range of factors," he said.

Jones pointed to the two Chechen Wars that took place in the 1990s. Russia negotiated a cease-fire in 1994, which ended the first war, but then restarted another war three years later and ramped up its onslaught.

In this scenario, Russia could hope that the US and other Western countries lose interest in the conflict and in supporting Ukraine.

"That would eventually change the balance of power in Russia's favor and allow it to reconquer territory the way it ideally wanted to in February," Jones said.

A peace deal

It is possible that the war could end with a peace deal, though a settlement is difficult because of Russia's and Ukraine's different goals and what they both view as their rightful territory.

"I think Vladimir Putin is in too deep at the moment. He's committed far too much political and military capital right now to extract himself from the war without very clear successes," Jones said.

Jones said that while it is not clear what Putin would accept as a "success," he might settle for Russia taking parts of Donetsk, Luhansk, Zaporizhia, and Kherson Oblasts, which he could then frame as his intended goals.

The more complicated question is what Ukraine would be willing to give up in any peace deal. Jones said it would be almost "politically suicidal" for any leader in Kyiv to give away any Ukrainian territory.

Russian victory

When it began its unprovoked invasion of Ukraine, Russia's goal was to take over the country completely.

Jones said it is important to note that Ukraine has already achieved a significant victory in preventing Russia from achieving that goal.

"Arguably, at least up to February 2022, the third most powerful military army in the world behind the US and the Chinese was the Russians. So they've already prevented a Russian blitzkrieg operation to take the capital, overthrow the government, and either integrate it into Russia or establish a puppet government," he said.

It is unlikely now that Russia would be able to turn the war around entirely and achieve its original aims, but it could accept a "victory" in the form of a peace deal in which it takes more territory than it had before the invasion began.

Russian retreat, Ukrainian victory

As long as Putin is at the country's helm, it would be very unlikely that Russian forces would retreat entirely, Jones said.

"In Russia, bad things happen to rulers who lose wars," Mark Cancian, a retired US Marine colonel and CSIS senior advisor, previously told Insider.

But despite Russia's strongman facing discontent at home due to rising war casualties, the partial mobilization of reservists, and an economy damaged by sanctions, he appears to show no signs of backing down.

Though the chances of him being overthrown in a coup are perhaps higher than ever, experts have previously said the Russian leader has made his regime "coup-proof" through a culture of distrust among Russia's intelligence agencies.

However, a total Russian retreat could be possible if Putin were to be ousted or die. Rumors have also long swirled about his alleged health problems, though US intel and military experts have warned that there is no credible evidence that he is ill.

Ukrainians believe outright victory is possible. Svitlana Morenets, a Ukrainian journalist who works for The Spectator news magazine in the UK, spoke a debate entitled "Is it time to make a peace in Ukraine."

The plan is not for years of battle but the military defeat of Russia, she said. She highlighted Putin's climbdown over the "grain corridor" as an example of Russia's weakness.

Long-term war

Not all wars end with a clear victory for one side. Another possibility is that fighting continues to rage on without any cease-fire or settlement, which, according to Jones, could go on for years.

It could involve special forces fighting back and forth on contact lines, guerilla action from Ukraine in Russian-controlled territories, and long-range bombardment of Ukrainian territory from Russia or Belarus.

In its current phase, the conflict appears to have become a war of attrition. Rather than taking more territory, Russia's objectives in the current stage of war seem to be to weaken Ukraine's resources, economy, and army.

It is unclear which side would be able to hold out for longer, though Russia has experienced significant losses in terms of soldiers and weapons.

According to the Carnegie Endowment for International Peace, the newly appointed Russian General Sergey Surovikin plans to build a solid line of defense in occupied territories and effectively freeze the war over the winter.

Russia would not seek to begin any new large-scale offensive into Ukrainian territory at this time and would take the time to build back up its fighting capabilities, the think tank said.

Nuclear war and/or NATO intervention

Putin has repeatedly made nuclear threats since he began the invasion of Ukraine and, in September, claimed that it was "not a bluff."

Western countries and experts are divided on how seriously to take the threats.

Jones said that there were big risks involved in using nuclear weapons, especially if Putin detonates them in territories he has been claiming are Russian. There would also be a risk of nuclear fallout on Russian territory due to proximity.

If Russian forces face a full-scale military rout, Putin could use a battlefield nuclear weapon, but Jones said the risks of using nuclear weapons would likely outweigh any benefits.

"There are a lot of risks involved in making that nuclear taboo, politically, diplomatically. What would that spell for Vladimir Putin's regime? I think the US has already communicated pretty forcefully that all bets are off if Russia were to use nuclear weapons," he said.

It is unclear whether NATO would get involved in that scenario, Jones said. One senior official previously said that a Russian nuclear strike could trigger a "physical response" from NATO itself.

However, Jones said that NATO declaring war on Russia could create a major war that could pull in other countries like China, which is an outcome that the organization likely wants to avoid.

To avoid that scenario, NATO would likely first turn to increased sanctions and support Ukraine with weapons.