Ukraine’s counteroffensive is now into its fourth month. Kyiv’s forces, bolstered by Western tanks and weapons, are putting pressure on Russian positions but have yet to achieve a major breakthrough.

But all across Ukraine, there is a sense that things could change very quickly. A section of defences could collapse, and fortunes could turn.

Sky News spoke to military expert Sean Bell about the different parts of the frontline and how each could be a flashpoint, from crossing the Dnipro in the west to the push to liberate Bakhmut in the east.

We’ve zeroed in on five locations and ask, is this where the war could be decided?

Can Ukraine break through in Zaporizhzhia?

The southern battle-zone in the Zaporizhzhia region is perhaps the most talked about part of the war at the moment.

Bell says this so-called land bridge between Crimea and the Donbas is “the least hard place” for Ukrainians to liberate the most territory.

Ukrainian forces are slowly but steadily pushing south but are coming up against defensive emplacements that Russia has spent months building.

The Surovikin line, named after a Russian general, extends through the area, a triple layer of defences comprising an anti-tank ditch, dragons’ teeth obstacles and then defensive positions in trenches.

If Ukrainian forces are able to pierce through in Zaporizhzhia and reach the coast of the Sea of Azov – or at least get close enough to hit the remaining territory with artillery – it would effectively cut Russian forces in half.

“If they can break through all those defences then suddenly there could be a rout of Russian forces in that land bridge,” Bell says.

There has been evidence so far during the counteroffensive that Ukraine has been keeping much of its Western tanks and best-trained troops in reserve, waiting for a breakthrough somewhere along the line.

Now, it seems, some of these tanks are being sent in to fight in the battle for Zaporizhzhia.

“You are never sure what will be the chink that will break the dam, you will never know until the crack emerges and the floodgates open.

“The question is whether the Ukrainians then have the stamina and the morale and the equipment to take advantage of it.”

Encircling a ruined city – and pinning down Russian forces

The city held out for so long. Waves and waves of Russian soldiers – many of them conscripts and former prisoners – were sent against Ukrainian defences and again and again Bakhmut held.

It was a controversial decision to keep defending the city, and there were many in the West who argued it was a mistake, but in the end it allowed Ukraine to inflict huge casualties on Russia and allow Kyiv time to get hold of Western tanks.

Russian forces, in particular Wagner Group mercenaries who are no longer involved, took the city at great cost.

Bakhmut does not exist as a city in the way it did before. Months of constant shelling by Russian forces have raised it to the ground.

It has little strategic value, but as a propaganda piece it is huge for Vladimir Putin.

Now, Ukraine is gaining ground around it. Could Bakhmut be liberated?

Bell says: “Bakhmut is one of those iconic places and Russia made a big thing of taking it, lost tens of thousands of lives taking it and will not want to lose it again.

“Most of the reports are the Ukrainian progress rather than Russian, but it doesn’t feel like there’s any momentum at the moment.

“Ukrainian pressure there is all designed to fix Russian forces in place.”

Is Russia pushing back in Kharkiv?

One of the main efforts of Russian forces – apart from holding back Ukrainian advances – is trying to take territory in the northeast, near Kharkiv.

Ukraine had great success in that arena last year, carrying out stunning advances around Kharkiv city.

Not only did they buy valuable breathing space for the ‘Hero City’, they liberated swathes of territory, including Kupyansk and Izium.

Now Russian troops are seeking to reverse some of those gains.

“The lines of communication there are very short for the Russian forces,” Bell says.

This is because of how close things are to the Russian border. Unlike in other parts of Ukraine, it’s much easier for Russia to resupply and communicate with its troops in the Kharkiv region.

In recent weeks they have claimed to have made advances, and fighting has been fierce and bloody.

Bell adds: “Russia has not been effective at conducting offensive operations since the start of the war – and that was when they had mercenary support with the Wagner Group.

“So it’s no great surprise that the Russian military are struggling to make progress.”

Crossing the Dnipro while Russia is busy elsewhere

One of the least talked about areas of the frontline is the River Dnipro, near the city of Kherson.

When Ukrainian forces swept through the region and liberated the city last year, the water became the new boundary between them and Russian forces.

This, Bell says, is why Russia blew up the Nova Kakhovka dam in June this year, sending torrents of water over the landscape.

“By blowing the Kakhovka dam that basically said ‘right Ukraine you are not going to be able to cross the Dnipro and we are going to leave it relatively unprotected’.”

That may have been true a few months ago, but the land is starting to dry out, presenting an opportunity for Ukraine.

“It’s a lot more accessible now and almost certainly isn’t the Russians’ main focus,” Bell says.

“It leaves them vulnerable down that flank.”

There are even reports that Ukraine has managed to land troops on the other side of the Dnipro.

But while that is progress for Kyiv, it’s not the same as establishing a beachhead from which they can deploy tanks and heavy weapons.

Bell compared it to D-Day, when the Allies managed to establish control over a chunk of French beach in June 1944 and held it until they could get armour on the ground and push outwards.

But he added that the more Ukraine puts pressure on Russian forces there, the more Kremlin commanders will have to reckon with a difficult choice: weaken their forces elsewhere to shore up the Dnipro, or risk a breakthrough across the water…

Drones, explosives and raids on Crimea

While it’s not on the frontline, Ukraine has certainly brought the war to Crimea in recent months.

Wave after wave of maritime drones are harassing Russian ships in the area, the Kerch Bridge has been hit multiple times and Ukrainian special forces have reportedly struck on the peninsula itself.

Crimea is home to Vladimir Putin’s prized Black Sea Fleet and is of huge strategic value due to its location on the Black Sea.

It has been in Russian hands since it was annexed in 2014 but Volodymyr Zelenskyy has vowed to return it to Ukraine.

Still, it’s very heavily fortified and will be very difficult to capture by force. Indeed, in the Second World War the Axis forces led by Nazi Germany lost 30,000 men in pursuit of Crimea.

So why is Ukraine attacking it? Because putting aside the prospect of seizing the territory, it helps their forces elsewhere.

Bell says “Ukraine has made clear its intent to take it, and what that does is it forces Russia to keep forces back to protect it.”

Russia might have 150,000 soldiers in Ukraine, but if it puts them all on the frontline then there is no one to defend Crimea if Kyiv’s forces make a breakthrough.

“The more that Ukraine threatens Crimea, the more Russia has to protect it and take its forces away from the frontline.”