Russia making small gains near Severodonetsk as Ukraine shells Snake Island

June 22 (UPI) -- The Russian military has captured additional settlements around the key eastern city of Severodonetsk as it moves to further isolate the largest remaining area in the Donbas that's not entirely under Moscow's control.

Russia has been trying for weeks to defeat Ukrainian forces in Severodonetsk and controls most of the city, but it's struggled to capture isolated pockets of Ukrainian resistance there.

Military officials say that Russian forces are pressing forward with Moscow's new strategy of cutting off routes to the city by occupying villages and targeting bridges. Ukrainian officials said recently that Russia controls more than 80% of Severodonetsk.

Roman Vlasenko, head of Severodonetsk's military administration, said Wednesday that the Kremlin took control of nearby Toshkivka this week and has since captured Pidlisne and Mala Dolyna, which are located just southwest of Severodonetsk. Russia also scored gains in trying to capture nearby Hirske, Vlasenko said.

Moscow has also intensified attacks in Lysychansk, another key eastern city, which is still mostly under Ukrainian control.

"The Russians are approaching Lysychansk, entrenching in nearby towns," Serhiy Haidai, head of the Luhansk regional military administration, said according to CNN. "The city is being shelled by aircraft. It is not easy for our soldiers to keep the defense."

A Ukrainian flag is seen on a street in Kyiv, Ukraine, on June 13. The Russian war in Ukraine began on February 24 and is close to entering its fifth month. Photo by Oleg Petrasyuk/EPA-EFE

Meanwhile, Ukraine's army said Wednesday that it's carried out airstrikes on Russian positions on Snake Island. The move, it said, caused "significant losses" to Russian forces. Kyiv's southern operational command said that "various forces" took part in the airstrikes, which limited Russian capability in the Black Sea.

Snake Island became somewhat famous in the early days of the war when a pocket of Ukrainian forces were defiant and refused to surrender to invading Russian troops.

Russian attacks on Izyum and Lyman toward Slovyansk in the Donetsk region appear to have stalled because of Moscow's concentration on Severodonetsk, the Institute for the Study of War told The Washington Post.

Fully capturing the Donbas region in eastern Ukraine has been the primary goal of Russia's military campaign since April, when Moscow declared a "new phase" of its campaign.

The Donbas region, which is comprised of Luhansk and Donetsk oblasts, has long been of particular interest to Moscow -- as it shares a border with Russia and for years has been home to a large segment of pro-Russia separatists who have fought the Ukrainian government. Russia built up its troop presence for months along its border with the Donbas and Russian President Vladimir Putin declared Luhansk and Donetsk as "independent" regions in the days before the invasion.

Elsewhere, Russian forces have renewed attacks farther north in Kharkiv, which is Ukraine's second-largest city. The new shelling attacks killed more than a dozen people there, according to Kharkiv Gov. Oleh Synyehubov.

To the south, Russian missile and artillery strikes targeted parts of the Kherson, Zaporizhzhia, Dnipropetrovsk, Mykolaiv and Odesa regions, Ukrainian officials said.