By Conor Humphries
KYIV (Reuters) - The capture of a sleepy Soviet-era factory town in Ukraine's industrial heartland has become the focus of Russia's invasion as President Vladimir Putin seeks to rebuild momentum after a failed attempt to take the capital Kyiv.
If Russia can capture Sievierodonetsk, and its smaller twin Lysychansk on the higher west bank of the Siverskyi Donets river, it will hold all of Luhansk, the first of the two Donbas provinces that Putin has placed at the heart of his campaign.
The city, much of it reduced to rubble by months of attacks culminating in two weeks of intense bombardment, offers little strategic gain beyond its rail and road connections, security experts say.
But it has symbolic value as the administrative centre of the part of Luhansk that remained under Ukrainian control when Russian-backed separatists seized the rest in 2014.
"The capture of Sievierodonetsk and reaching the boundaries of Luhansk region would be more important for the leadership of Russia from a political point of view ... as a victory and achievement of their military and political goals," said Ukrainian military analyst Kostyantyn Mashovets.
"In military terms, of course it will make the situation worse for us, but it won't be crucial."
Sievierodonetsk was founded in 1934, during Josef Stalin's second Soviet five-year plan, as a suburb of Lysychansk to house workers from a chemical and fertiliser factory, which survives to the present as the Azot (Nitrogen) plant.
For most of its history it has been a typical Soviet provincial town. Streets of identical high-rise apartments were interspersed with parks and wide, tree-lined streets, while residents picnicked beside the Siverskyi Donets river and in forests nearby.
When separatists seized around one-third of Luhansk province, including the capital of the same name, Sievierodonetsk became the administrative centre of the Ukrainian-controlled part of the region.
It also became a hub for both the Ukrainian military and for aid organisations operating in the area. Many soldiers spent their down time in the city when they were rotated from the front, before the invasion brought the conflict closer.
From a peak of around 110,000 people a decade ago, fewer than 15,000 remain in the town now, regional governor Serhiy Gaidai said last week.
He said the shelling of recent weeks had damaged 90% of the buildings in Sievierodonetsk and all of its critical infrastructure. He said 60% of its housing would have to be rebuilt.
For now, the last remaining access and evacuation route, leading southwest towards the town of Bakhmut, remains open under Ukrainian control - albeit pitted by shell-craters after several Russian attempts to seize it and cut off the twin towns.
"It's my city, it's my home ... I'm not going anywhere," the self-appointed head of a bomb shelter who identified herself as Tetiana told the Ukrayinska Pravda news outlet.
"There are still walls in my apartment," she said. "I won't have anything - but I will survive."
(Writing by Conor Humphries; Editing by Kevin Liffey)