The Russian Defence Ministry said Saturday that Moscow's forces have captured five villages as part of a renewed ground assault in northeastern Ukraine.

Ukrainian officials haven't officially confirmed whether Russia had taken the villages, which lie in a contested “gray zone” on the border of Ukraine's Kharkiv region and Russia.

Ukrainian journalists reported that the villages of Borysivka, Ohirtseve, Pylna and Strilecha, were taken by Russian troops on Friday. Russia said the village of Pletenivka was also taken.

The Institute for the Study of War said Friday that geolocated footage confirms at least one of the villages was seized. The Washington-based think tank described recent Russian gains as “tactically significant.”

The renewed assault on the region has forced more than 1,700 civilians residing in settlements near the fighting to flee, according to Ukrainian authorities. It comes after Russia stepped up attacks in March targeting energy infrastructure and settlements, which analysts predicted were a concerted effort by Moscow to shape conditions for an offensive.

Russia's recent push in Kharkiv also seeks to exploit ammunition shortages before promised Western supplies can reach the front line, and pin down Ukrainian forces in the northeast and keep them away from heavy battles underway in the Donetsk region where Moscow's troops are gaining ground, analysts said.

Russian military bloggers said the assault could mark the start of a Russian attempt to carve out a “buffer zone” that President Vladimir Putin vowed to create earlier this year to halt frequent Ukrainian attacks on Belgorod and other Russian border regions. Fears also mount that without adequate supplies, Russia might even be able to cut supply routes and besiege the city of Kharkiv, where 1.1 million people reside.

Ukrainian officials have downplayed Russian statements about captured territory, with reinforcements being rushed to the Kharkiv region to hold off Russian forces.

On Telegram, Kharkiv region Gov. Oleh Syniehubov said that heavy fighting continued in the areas around Borysivka, Ohirtseve, Pylna and Oliinykove, but that the situation was under control and there was no threat of a ground assault on the city of Kharkiv.

Ukrainian President Volodymyr Zelenskyy confirmed Friday evening that Russian forces were expanding their operations. He also called on the country's Western allies to ensure that promised deliveries of military aid would swiftly reach the front lines.

“It is critical that partners support our warriors and Ukrainian resilience with timely deliveries. Truly timely ones,” he said in a video statement on X. “A package that truly helps is the actual delivery of weapons to Ukraine, rather than just the announcement of a package.”

The attack was launched from two areas in the Kharkiv region early Friday, Ukrainian officials and analysts said. Russian assault groups attempted to break through Ukrainian defensive lines in the city of Vovchansk and in the region north of the village of Lyptsi.

On Saturday, Russia continued to pummel Vovchansk with airstrikes and grad rockets as police and volunteers raced to evacuate residents. At least 20 people were evacuated to safety in a nearby village. Police said that 900 people had been evacuated the previous day.

Associated Press journalists who accompanied an evacuation team described empty streets with multiple buildings destroyed and others on fire. The road was littered with newly made craters and the city was covered in dust and shrapnel with the smell of gunpowder heavy in the air. Mushroom clouds of smoke rose across the skyline as Russian jets conducted multiple airstrikes.

“In the current moment, the situation in Vovchansk and the settlements along the border (with Russia) is incredibly difficult. Constant aviation strikes are carried out, multiple rocket missile systems strikes, artillery strikes,” said Tamaz Hambarashvili, the head of Vovchansk City Military Administration.

"For the second day in a row, we evacuate all the inhabitants of our community who are willing to evacuate.”

AP journalists witnessed nine air attacks during the three hours they were there.

“I think that they are destroying the city to make (local) people leave, to make sure there are no militaries, nobody. To create a 'gray zone,'” Hambarashvili said.

In the meantime, artillery, mortar and aerial bombardments hit more than 30 different towns and villages in the region on Saturday, killing at least three people and injuring five others, Syniehubov said.

Separately, Ukrainian forces also launched a barrage of drones and missiles on Friday night, Russia's Ministry of Defence said, with air defence systems downing 21 rockets and 16 drones over Russia's Belgorod, Kursk and Volgograd regions. One person died in a drone strike in the Belgorod region, and another in the Kursk region, local officials said.

Another strike set ablaze an oil depot in Ukraine's Russian-occupied Luhansk region, killing four people and wounding eight more, Leonid Pasechnik, the region's Moscow-installed leader, said on the messaging app Telegram on Saturday.

There was also shelling in the Russian-occupied Donetsk region Saturday, where three people died when an explosion hit a local restaurant, said Denis Pushilin, the area's Kremlin-appointed leader. Eight more people were wounded, including a child.

In the war's early days, Russia made a botched attempt to quickly storm Kharkiv but retreated from its outskirts after about a month. In the fall of 2022, seven months later, Ukraine's army pushed them out of Kharkiv. The bold counterattack helped persuade Western countries that Ukraine could defeat Russia on the battlefield and merited military support.