Why is the Donetsk region so important for Ukraine's defense?

A key takeaway from the Alaska summit is that Russian President Vladimir Putin wants to freeze the war in Ukraine along its current front line in exchange for the surrender of the rest of Donetsk Oblast.

Russia holds about 70% of the region, including the regional center of the same name, after more than a decade of fighting in which Donetsk and neighboring Luhansk are the bleeding heart of the conflict.

If Russia were to gain all of Donetsk, it would solidify its internationally unrecognized claims to the region, as well as prevent further heavy military losses.

For Ukraine, its withdrawal from western Donetsk would mean a heavy loss not only of land, with the prospect of a new influx of refugees, but also the fall of a bastion against any future Russian offensive, writes BBC.

Here we look at why territory is so important.

What does Ukraine still control?

A Reuters estimate suggests Ukraine still holds about 6,600 sq km of territory in Donetsk.

A quarter of a million people remain there, local authorities said recently.

The main urban centres include Kramatorsk, Slavyansk, Konstantinovka and Druzhkovka.

Ukraine's main industrial region is the Donbass (Donetsk Basin), although its economy has been devastated by the war.

“The reality is that these resources are probably not going to be available for perhaps a decade, at least because of the [land] mines...“, Dr Marnie Howlett, a lecturer in Russian and East European politics at Oxford University, told Reuters.

"These lands have been completely destroyed, these cities have been completely razed to the ground.“

Where is the military value of the territory?

A recent report by the US Institute for the Study of War (ISW) describes a "fortress belt" stretching 50km across western Donetsk.

"Ukraine has spent the last 11 years investing time, money and effort in strengthening the fortress belt and building a significant defensive, industrial and defence infrastructure", it said.

Reports from the region speak of trenches, bunkers, minefields, anti-tank obstacles and barbed wire.

Russian forces attacking in the direction of Pokrovsk "are engaged in an attempt to capture it, which will probably take several years“, the ISW claims.

The fortifications are certainly part of the Ukrainian defences, but the topography is also part of them.

"The terrain is relatively easily defensible, especially the Chasov Yar height, which is the base of the Ukrainian line“, Nick Reynolds, a research fellow in land warfare at the UK's Royal United Forces Institute (RUSI), told BBC News.

However, he added: "If you look at the topography of Donbas, eastern Ukraine as a whole, the terrain is not particularly favourable to the Ukrainians.“

"The city of Donetsk is on high ground. Everything is downhill to the west, which is not good for the Ukrainians in terms of conducting defensive operations.“

"It's not just about drawing attention to the close combat or the difficulty of climbing and descending the hill, but also about observation and therefore the ability to coordinate artillery fire and other forms of fire support without using drones.“

"Likewise, high ground is better for radio propagation, better for coordinating drones.“

Chasov Yar, which the Russians recently claimed to have captured, "is one of the last high ground the Ukrainians control," he says.

Intelligence through satellite imagery, whether provided by Ukraine's international partners or commercially, is very important, Reynolds notes, "but "is not the same as being able to directly coordinate their own tactical missions."

Does the Russian military need all of Donetsk?

Western Donetsk is only a small part of the front line, which stretches for about 1,100 km, but it has been the target of some of the fiercest Russian attacks this summer.

But if Moscow had directed its ground forces in a different direction, it is doubtful that they would have made more progress.

"To the south, the front line in Zaporizhia is now very similar to the one in Donbas, so it would simply mean fighting through extensive defensive positions," Reynolds said.

"The Russians face the same problem trying to break through to the north, so they certainly won't be pushing an open door."

Will Ukraine be able to rebuild its defenses on West?

In theory, in the event of a peace agreement, the Ukrainians could move their line further west.

Of course, there would be the problem of difficult terrain, and building deep defensive facilities would take time, even with the help of civilian contractors who would not have to work under fire.

But theory is one thing, and the Russian land warfare scholar cannot imagine how the Ukrainian army would give up western Donetsk without a fight.

"Even if the Trump administration were to try to use current U.S. support or security guarantees as leverage," says Nick Reynolds, "based on past Russian behavior, based on the explicitly transactional approach that the U.S. administration has taken, it is difficult to see how the Ukrainian government would want to give up this territory."

Ukrainian President Volodymyr Zelensky has said his country would reject any Russian offer to give up Donbas in exchange for a ceasefire, arguing that the eastern territory could be used as a springboard for future attacks.