DONETSK, Ukraine (AFP) - Resurgent government forces on Saturday hoisted the Ukrainian flag over pro-Russian rebels' main stronghold after a devastating shelling onslaught levelled much of the city but delivered Kiev its biggest success of the campaign.
The self-proclaimed mayor of Slavyansk confirmed to AFP that insurgents had abandoned the rustbelt city of 120,000. A local resident said by phone that barricades once manned by the camouflage-clad gunmen stood abandoned since the early morning.
Images posted on YouTube showed helmeted troops carrying dozens of grenade launchers out of the barricaded Slavyansk city hall building as the blue-and-yellow national banner streamed under a blazing blue sky.
Kiev's ability to win back Slavyansk - home to one of the country's biggest weapons storage facilities that fell to the insurgents in early April - marks a key turning point in three months of low-scale warfare that has threatened the very survival of the ex-Soviet state.
Ukrainian Interior Minister Arsen Avakov said the withdrawal was led by senior militia commander Igor Strelkov - alleged by Kiev to be a colonel in Russia's GRU military intelligence unit.
Both Strelkov and Moscow deny any GRU link, despite Western claims that the Kremlin is covertly funding and arming the uprising to destabilise Kiev's new pro-European leaders and retain control over Russian-speaking eastern regions of Ukraine.
Ukrainian President Petro Poroshenko stormed to victory in a May 25 election thanks to his vow to quickly resolve the country's worst crisis since independence in 1991.
Most analysts think the 48-year-old chocolate baron desperately needed an early battlefield victory to secure the trust of Ukrainians frustrated by their underfunded army's inability to stand up to what they see as Russian aggression.
Poroshenko immediately vowed to press on with his offensive and flush out "terrorists who are entrenching themselves in large cities".
"This is not a full victory and no time for fireworks," the Western-backed leader said in a statement.
"I am nowhere near euphoric. The situation is very difficult," he cautioned. "A lot of challenges lie ahead."
Strelkov himself had told the pro-Kremlin LifeNews channel on Friday that his units "will be destroyed... within a week, two weeks at the latest" unless Russia moved in its troops.
The militia commander tweeted on Saturday that President Vladimir Putin's repeated vow to use "all available means" to protect his compatriots in Ukraine - a neighbour he referred to as "New Russia" - now looked like an empty promise.
"They filled us with hope and abandoned us. Those were fine words by Mr Putin about protecting the Russian people, defending New Russia. But only words," Mr Strelkov wrote.
Slavyansk is the symbolic heart of an uprising sparked by the February ouster of a pro-Kremlin administration in Kiev and fuelled by Russia's subsequent seizure of Crimea.
Relentless artillery and sniper fire across a dozen blue-collar cities and towns have since claimed more than 470 lives and left Western leaders frustrated by repeated mediation failures.
Clashes in the economically-vital border regions of Lugansk and Donetsk picked up with renewed vigour when Mr Poroshenko tore up a 10-day ceasefire agreement earlier this week.
His decision was immediately followed by the launch of a "massive" offensive by Kiev that prompted Germany and France to spearhead a new push for an immediate and lasting ceasefire.
US President Barack Obama has also urged Mr Putin to commit himself to a solution in Ukraine that could stave off punishing American sanctions against Russia's banking and arms exports sectors.
And uneasy EU leaders are hoping that a firm promise by Mr Putin not to meddle in Ukraine can take pressure off the 28-nation bloc to adopt punitive steps that could damage their own strong energy and financial ties with Russia.
But Mr Poroshenko's call for European-mediated truce talks on Saturday was left unanswered by Moscow and the separatist command.
"The date, place and format are being discussed, but there have been no major changes yet in the progress of preparations for consultations," a source in Moscow told Russia's Interfax news agency.
The 43-year-old Mr Strelkov remains one of the uprising's most mysterious but also powerful figures, who effectively headed the new Kiev leadership's most-wanted list.
He holds the title of "defence minister" of the Donetsk People's Republic and is also the chief of the Slavyansk militia.
Mr Strelkov was linked to the April capture and detention of seven OSCE monitors in Slavyansk who were eventually released after an eight-day ordeal following intervention from Moscow.
Kiev has published what it says are intercepted conversations between him and Putin's special envoy Vladimir Lukin talking about the OSCE monitors.
"We want to liberate Ukraine from the fascists," Mr Strelkov told a Russian tabloid after his units had captured Slavyansk.