Mariupol, Ukraine - Glowing red sparks burst and skitter across the concrete floor around a giant furnace as men at Ilyich Iron and Steel Works monitor the rolling of glowing slabs.

The works are cavernous, so big it feels like a skyscraper could be built here on its side. Here and there a surprisingly small number of steelworkers pass giant placards exhorting them, Soviet style, to higher standards.

This is one of Ukraine's largest steel plants and it is squarely in the sights of Russian-backed rebels who have a front line just down the coast from Mariupol.

Hand painted murals adorn the floor of the Ilyich Iron and Steel Works in Mariupol [John Wendle/Al Jazeera]

The self-styled Donetsk People's Republic will need to capture Ilyich and its nearby sister plant Azovstal, also owned by billionaire oligarch Rinat Akhmetov, in order to create anything resembling a functioning economy for the unrecognised state - and they know it.

Ceasefire or not, everyone in Mariupol remains tense.

When asked about the possibility of taking Mariupol, the largest government-held city in rebel-controlled Donetsk province, Denis Pushilin, a rebel politician involved in peace talks, said: "We'll do everything possible to make it happen through political means," Russian media reported.

The government in Kiev said the rebels are playing an even more shadowy game, trying to destabilise an already shaky situation in a town briefly controlled by rebels early in the conflict and home to potentially large population of people who sympathise with the cause.

A woman passes a sign for a bomb shelter in Vostochniy, a neighbourhood in Mariupol near the front line [John Wendle/Al Jazeera]

"They are intentionally bombing Avdiivka to destroy the coke plant, so that Mariupol's factories close, so there's a social revolt in Mariupol," said Prime Minister Arseniy Yatsenyuk, during a television interview last Friday.

Though shelling continues near the coking plant at Avdiivka, the work somehow goes on - albeit at a much smaller scale and at great risk.

"Last night, a piece of shrapnel from another shell struck our natural gas pipeline. We responded quickly and continue to work," wrote Avdiivka's general director Musa Magomedov on his Facebook page, adding they now "wait for a real peace. Even though spring also seemed infinitely far away, it is now here".

Magomedov's tone was hopeful, but, even if there is peace, the situation in the Donbas - the economically depressed industrial basin that makes up Donetsk and Luhansk provinces - is already dire. Towns such as Avdiivka, Mariupol, Debaltseve, Luhansk, Antrasyt and Krasnodon form links in a vast industrial chain that once was the pride of the Soviet coal and steel industry.

Steelworkers manoeuvre scrap into a melting oven [John Wendle/Al Jazeera]

Long neglected by Kiev and in need of a profound overhaul of infrastructure that was made impossible by corruption at the highest levels - after the collapse of the Soviet Union, the Donbas slowly slipped into the grip of oligarchs, poverty and irrelevance.

Rebel leaders, however, see the formidable empire that Akhmetov built, and envision a way to fund their state.

Yuriy Zinchenko, general director of Metinvest's Ilyich steelworks, agreed that Mariupol is now a strategic goal for the rebels, but he disagreed about the economics.

"Everything has already been destroyed," he said. "I would say that almost all - that 95 percent of the logistics infrastructure, railroads and et cetera - have been destroyed. It's the biggest problem we have," he said.

But that doesn't seem to matter to the rebels and the government - both sides still want the city.

"If fighting breaks out in the city then nothing will be left of it," said Zinchenko.

He said the company is continuing to pay salaries - which, along with Azovstal employs 10 percent of the city, and is investing in infrastructure for the future.

"We've heard no shelling for a few days, so that's some positive news at least," he said.

A steelworker at Ilyich Iron and Steel Works [John Wendle/Al Jazeera]

That Mariupol would be a gem in the crown of the rebels makes people here nervous. And few say the current ceasefire - though more respected than the first - will last.

What is more, Mariupol's geographic situation puts it in the crosshairs, since the city lies along what people here are calling the "land bridge" - the strip of territory down Ukraine's southeastern coast that, if conquered, would link rebel-controlled territory in the east to Russian-controlled Crimea.

In a dilapidated boarding house near Red Lighthouse St, people from outlying villages have sought refuge from the fighting. The most recent influx of displaced people has been from Shyrokyne, the scene of continued shelling, a small village lying between rebel and government territory on the coast.

A fighter with the volunteer Azov Battalion at a base in Mariupol [John Wendle/Al Jazeera]

"There were tanks here and tanks there, everyone shooting at each other. And we were just sitting there, shaking underground. It was pure animal fear," said Vera Logozinskaya, a retired fish factory worker outside the boarding house. "God forbid the same thing happens here."

Few said the ceasefire will last.

Igor, a taxi driver who ferries train passengers in his old Hyundai from Berdyansk to Mariupol - the train does not run here any more after a rail bridge was blown in January - said he sees fewer military vehicles heading towards the front these days.

"Before the ceasefire, there were always lots of military columns on the road heading into Mariupol. Now there are less, but there are still some heading towards the front."

Across the road from the giant belching stacks of Azovstal, a small group of fishermen late last week stood on a trash strewn bank, hoping to get a nibble from the polluted waters beat to a hard silver finish by the setting sun.

Valery Govailchuk, a retired steelworker, cast his rod towards the opposite bank as water poured into the river through a rusty sluice that runs under Azovstal from the Sea of Azov. He was cynical and jaded, but not nervous.

"It's not fighting over there, they're just taking potshots at each other while they wait for those in power to decide what's next," Govailchuk told Al Jazeera. "I'll keep fishing here until Putin decides to take Mariupol for real."

Source: Al Jazeera