Deadly fighting has broken out again between the government and rebels around the strategically important airport outside Donetsk, a continuing source of friction that is testing the resilience of a recent cease-fire agreement.
Nine Ukrainian soldiers and three civilians were killed during heavy shelling on Sunday, government officials announced. Andriy Lysenko, an army spokesman, said seven soldiers died when a tank shell hit their troop transport. It was the deadliest attack since the cease-fire was announced on Sept. 5.
President Petro O. Poroshenko has called the cease-fire the keystone to his peace plan for the country, and in a nationally televised news conference on Thursday said he had “no doubt that the biggest, most dangerous part of the war is already behind us.”But at important positions held by Ukrainian forces, like the airport and the city of Debaltseve, a crucial junction between the largest rebel cities of Donetsk and Luhansk, shelling has only intensified in recent days.
The upsurge in violence comes at a particularly critical moment, as Russian, Ukrainian and rebel military officials are meeting to work out the boundaries of a buffer zone of 30 kilometers, about 19 miles, that, when finalized, could mark a neutral area in a new, frozen conflict.
“The line drawn on paper does not correspond to the current positions,” said Andrei Purgin, the deputy prime minister of the rebel Donetsk People’s Republic, who participated in the talks in Minsk, Belarus, that led to the cease-fire.
In an interview, Mr. Purgin said that fighting was taking place at contested points on the proposed demarcation line, which he said amounted to 30 percent of the border between the rebel republics and Ukraine.