DRUZHKIVKA, Ukraine — Longstanding strongpoints of Ukraine’s defense in the east have come under intense attack in recent days, according to the Ukrainian Army and Western military analysts.
That Ukrainian soldiers still hold the trench mazes and fortifications in two suburban towns, Avdiivka and Pisky, on the edge of the city of Donetsk is a testament to the value of their dug-in positions in the east. Ukraine’s strong defensive positions have slowed the Russian Army’s advance to a crawl, with only two large cities, Sievierodonetsk and Lysychansk, and a few dozen miles of territory changing hands despite thousands of soldiers killed on both sides.
It was unclear exactly why assaults on the fortifications have been intensifying, and the assaults are an exception to a general tapering off of Russian attacks in the eastern Donbas region, which had been the focus of the war for months. Some military analysts believe that the relative lull has been partly a result of Russian forces’ diverting to the south to fend off a Ukrainian counteroffensive there.
The two towns, mostly deserted and destroyed, are hardly big prizes to capture, but if they were to fall, that could ease Russian advances toward the three large cities in the Donetsk region remaining under Ukrainian control, Bakhmut, Kramatorsk and Sloviansk.
The Ukrainian army and paramilitary groups built the fortifications in the two towns during the eight years of low-intensity war after Russia’s 2014 military intervention in Ukraine to prop up a separatist region, the Donetsk People’s Republic. They are now among Ukraine’s easternmost positions.
Weaving through abandoned factories and mines, taking advantage of root cellars in country homes and using swamps as natural barriers, the defensive lines there have withstood countless assaults. After failing to flank Avdiivka, Russia began direct tank assaults this week, according to the Institute for the Study of War, a Washington-based research organization.
The institute noted Russian propaganda videos suggesting that Russian troops had overrun a position at the ventilation shaft of the Butiyka coal mine, which since 2015 had been the closest Ukrainian position to the city of Donetsk, a few miles from what the separatists claim is their capital.
The Ukrainian general staff has said the tank assaults did not push its soldiers from Avdiivka, but noted that they were a partial success, in a possible acknowledgment of the loss of the strategically and politically important position.
“For days in a row now, the enemy has not let up on attempts to attack,” the Ukrainian military governor of Avdiivka, Vitaliy Barabash, told Radio Liberty on Wednesday. “Everywhere is being hit by artillery and aviation” bombs.
The Russian military has also fired into the town with rockets that spray flammable material into the air and then ignite it, creating a giant fireball. The Russian thermobaric rocket system, nicknamed the Heatwave, is one of the most destructive weapons in Russia’s arsenal.
“People are living in horrible, inhuman conditions,” Mr. Barabash said. He said that about 2,000 civilians remained in Avdiivka out of a pre-invasion population of about 20,000. “Every day, the city is shelled about 20 times,” he said.
Overall, Russia’s campaign in Donbas has tapered off in recent weeks after the appearance on the battlefield of American HIMARS, the long-range rocket-launching system used to hit ammunition depots behind Russian lines, and the start of Ukraine’s counteroffensive around the southern city of Kherson, according to Serhiy Grabskiy, a former Ukrainian army colonel and commentator on the war for the Ukrainian news media. Russia has diverted about 10,000 soldiers from the attack on Sloviansk to defend the south, he said.
“Ukrainian forces created in the Donbas quite effective defensive positions over the past several years,” Mr. Grabskiy said in a telephone interview. The Russians “are frankly stuck in Donbas now without real success,” he said. “And they have a new headache: the south, which from the perspective of the Ukrainian armed forces is a more important strategic goal.”