Russia has increased its use of air force in support of artillery and ground troops who are trying to expand their territory in the Donbas region of eastern Ukraine, including the city of Sievierodonetsk, according to a British intelligence report on Saturday.
Ukrainian forces moved heavy weapons and howitzers toward the front line in Sievierodonetsk on Friday, pouring men and armor into the fight in an apparent refusal to pull back from a city Russia has pounded with missile fire for weeks. A Russian defense ministry statement on Saturday said Ukrainian forces were retreating from the city, a position that Ukrainian officials denied. The Ukrainian military administrator said overnight that Ukrainian troops had managed to push back Russian forces by 20 percent.
President Vladimir V. Putin's forces has made the heavily industrial Donbas region bordering Russia the focus of his military campaign after Russian forces failed to seize the capital, Kyiv, early in the conflict.
Moscow is unable to destroy Ukraine's air defense systems because of that.
Russia has deployed air power to support guided and unguided missile strikes in the second phase of the war, according to the British intelligence report on Sunday.