By Dan Peleschuk and Andrew Osborn
KYIV/LONDON (Reuters) - Russian forces are intensifying attacks on the eastern Ukrainian city of Avdiivka, seeking to encircle Kyiv's troops there as Moscow's war in Ukraine grinds on.
The fighting is reminiscent of a battle for another eastern city, Bakhmut, which fell to Russian forces last May after months of brutal urban combat.
Since Moscow launched its renewed offensive around Avdiivka in October, Ukraine's top general and Western military experts have made downbeat assessments of Ukraine's ability to break Russian lines.
In Kyiv and Western capitals, there is an acknowledgement that Russia's full-scale invasion more than 21 months ago, which Moscow calls a "special military operation", could drag on into a much longer war.
WHAT IS AVDIIVKA?
Avdiivka, which had a pre-war population of around 32,000, has been a frontline city since 2014, when it was briefly occupied by Moscow-backed separatists who seized a swathe of eastern Ukraine in what Kyiv and the West.
Avdiivka, much of it now damaged, is home to Ukraine's largest coke plant, a Soviet-era facility which before the war was one of Europe's top producers of the fuel.
The plant, which Moscow says is being used by Ukrainian forces as a base and weapons storage facility, is now the primary focus of Russian attacks.
Located just north of the Russian-occupied city of Donetsk in the industrial Donbas region, Avdiivka hosts deeply entrenched Ukrainian defences.
Today, just 1,500 residents - many sheltering in cellars and basements - are estimated to remain in Avdiivka, where officials say not a single building remains intact.
FIERCE FIGHTING
Ukrainian and Western analysts say Russia's renewed offensive on Avdiivka, its largest operation since the assault on Bakhmut, is proceeding at an extremely high human cost.
In a Nov. 27 update, British military intelligence said the fighting had contributed to "some of the highest Russian casualty rates of the war so far".
"Every day there are new fresh forces, regardless of the weather, regardless of anything - of losses," one member of Ukraine's 47th Separate Mechanized Brigade told Radio Liberty.
"But no matter what, they keep crawling, literally over the bodies of their own."
Andrei Gurulyov, a Russian lawmaker and retired military officer, has said the offensive has shown the need for Russian forces to improve their ability to attack.
Russian war bloggers, whom the Kremlin's media handlers have brought under tighter control, have acknowledged heavy losses on their own side but pointed to significant Ukrainian losses too.
The main war bloggers' collective account on the Telegram messaging service - "Operation Z: War Correspondents of the Russian Spring" - has given its more than 1.3 million followers detailed accounts of what it says is the steady but hard-won progress of Russian forces in Avdiivka.
It has described how they have been using air strikes with targeting assistance from special forces, artillery, drones, helicopters, tanks and infantry against heavily dug-in Ukrainian troops.
Semyon Pegov, a prominent Russian war blogger who has attended Kremlin meetings with President Vladimir Putin, has described Avdiivka, which Russians call Avdeevka, as "a fortress" with numerous concrete-reinforced bunkers.
Pegov, who has likened the fighting to trench warfare in World War One, said Russian forces took control of Avdiivka's industrial zone in recent days and that Russian cluster munitions were inflicting "huge losses" on Ukrainian forces.
The Russian defence ministry issues spare but regular updates. Unlike late Wagner mercenary chief Yevgeny Prigozhin, whose forces spearheaded the assault on Bakhmut, it does not offer predictions or set out its aims.
WHAT'S AT STAKE?
Both sides see Avdiivka as key to Russia's aim of wresting full control of the two eastern provinces of Donetsk and Luhansk - two of the four Ukrainian regions Russia says it has annexed but does not have full control of.
Avdiivka is seen as a gateway to Donetsk city, about 15 km (9 miles) to the south, whose residential areas Russian officials say have been regularly shelled by Ukrainian forces.
Pushing Ukrainian forces out of Avdiivka would be seen as enlarging the amount of territory Russia controls and making Donetsk city safer.
Seizing Avdiivka could boost Russian morale and deal a psychological blow to Ukrainian forces, which have made only incremental gains in a counteroffensive launched in June.
Mykola Bielieskov of the National Institute for Strategic Studies, an official think-tank in Kyiv, said taking Avdiivka would not "decisively" tip the situation in Moscow's favour but "would make the situation more tenable for occupied Donetsk as a major Russian logistics hub."
Bielieskov believes the campaign to capture Avdiivka is mostly driven by what he called the Kremlin's eagerness to "strengthen the hand of Western sceptics" who are calling for a cut in military and financial support for Kyiv, citing the limited impact of billions of dollars in military aid.