MOSCOW— The Ukrainian army retreated Thursday from key airport strongholds in the country’s conflict-battered eastern region, handing a symbolic gain for pro-Russian rebels amid a surge in violence that threatens to further unravel peace efforts.
The clashes at the Donetsk airport are part of escalating tensions in Ukraine as a cease-fire frays and Ukraine’s Western-allied government accuses Russia of sending forces over the border to bolster the insurgents.
Moscow denied the claims and traded accusations with Ukraine over which side was responsible for the latest bloodshed in the region: A shelling that killed at least seven people at a trolley stop in Donetsk.
Intensifying battles — including the showdown over the airport — have raised concern that rebels could be pressing offensives that could eventually undermine efforts to quell the violence that began last year. Ukraine’s pro-Russian factions have opposed moves to strengthen the country’s bonds with the European Union.
The Donetsk airport has emerged as the epicenter of near-constant battles. The terminal , which had been controlled by Ukrainian forces, was abandoned after a series of fierce rebel attacks that destroyed much of the building and caused dozens of casualties.
“Because this building was reduced to rubble, the decision was taken to withdraw Ukrainian fighters from this building to new lines,” military spokesman Vladislav Seleznyov told reporters in Kiev .
He said six soldiers had died in the recent clashes, and another 16 had been taken captive by pro-Russian rebels.
The development comes as Ukrainian officials raised new charges that Russia has resumed sending troops to reinforce the rebels.
During a speech at the World Economic Forum in Davos on Wednesday, Ukrainian President Petro Poroshenko said that Russia had sent 9,000 troops into eastern Ukraine.
Russia has routinely denied the accusations. Russian Foreign Minister Sergei Lavrov told reporters Wednesday that Ukraine needed to “show us the facts.”
But NATO Secretary General Jens Stoltenberg appeared to lend credence to Ukrainian claims, telling reporters that “for several months, we have seen the presence of Russian forces in eastern Ukraine, and we’ve also seen a substantial increase in the number of Russian heavy equipment in eastern Ukraine.”
The loss of the airport would mark a symbolic victory for the rebels, which have made the site a key goal for its fighters.
Ukrainian’s military spokesman, Col. Andriy Lysenko, suggested the battle was not over.
“We cannot say that we have completely withdrawn from the airport – this is a battlefield at the moment,” he told reporters. “Our military is not withdrawing, is not retreating.”
But the commander of the Azov battalion, a volunteer unit of the Ukrainian army at the Donetsk airport, declared the airport “lost” on the battalion’s Facebook account.
“The heroic defense continued for 242 days,” the battalion wrote on its Facebook page. “That is longer than the defense of Stalingrad and Moscow during the Soviet-German war, it is longer than a whole war can last, sometimes.”
Ukrainian officials, meanwhile, blamed the rebels for the attack on the trolley stop – adding that Russia bore responsibility for preventing such tragedies.
“The tragedy at the bus stop in Donetsk is our common grief,” Ukrainian Foreign Minister Pavlo Klimkin said in a Twitter post. “Peaceful Ukrainians are dying because of such terrorist attacks. Russia must stop the terrorists.”
Pro-Russian rebels initially claimed the shelling was an “act of sabotage” and that the people responsible for the attack had already been detained, according to Russian news service Interfax.
But self-proclaimed Donetsk People’s Republic head Alexander Zakharchenko later offered a new explanation, according to Interfax, telling reporters at the scene that “it was not saboteurs who did it” and said the trolley stop was struck by artillery fire coming from Avdiivka, a village in the Donetsk region.
It was unclear who controls the village.
Russia’s foreign minister Lavrov blamed Kiev, claiming that the attack on was a “crime against humanity” and a “gross provocation aimed at undermining efforts at a peaceful settlement of the Ukrainian crisis.”
On Wednesday night, representatives of Russia, Germany, France and Ukraine met in Berlin to discuss the conflict in eastern Ukraine, and reached an agreement on a dividing line from which government and pro-Russian separatist forces would pull back their heavy weapons.