Ukraine said on June 4 that its forces had recaptured 20 percent of the territory they had lost in the city of Syevyerodonetsk, the focus of a Russian offensive to take the eastern Donbas region, and could hold it for up to two weeks, when more Western artillery is expected to arrive.

Serhiy Hayday, the head of the Luhansk regional military administration, said Ukrainian forces continued to hold their positions inside Syevyerodonetsk and were pushing back Russian troops in several locations.

"As soon as we have enough Western long-range weapons, we will push their artillery away from our positions,” Hayday said. He described the situation in the region as “extremely difficult” with Russia using all its available forces to capture the industrial city.

“Fighting is now concentrated in Syevyerodonetsk because, as we understand it, the Russian army is throwing all its power, all its reserves in this direction,” he said on June 4.

Hayday said Russian forces were blowing up bridges across the Severskiy Donets river to prevent Ukraine from bringing in military reinforcements and delivering aid to civilians in Syevyerodonetsk.

Hayday's claim of Ukrainian advances could not immediately be verified. Ukraine’s military said Russia has reinforced its troops and used artillery to conduct "assault operations” in the city, which has been bombarded by Moscow's forces for weeks.

"The enemy is undertaking attacks on the city of Syevyerodonetsk with artillery support, it has strengthened its troops with the mobile reserves of the Second Army Corps, the fighting in the city continues," the Ukrainian military said on June 4.

But it added that Russian forces had retreated after failed attempts to advance in the nearby town of Bakhmut and cut off access to Syevyerodonetsk.

British intelligence estimates that Russia now controls more than 90 percent of the Luhansk region in eastern Ukraine and is likely to get full control of the region in the next two weeks.

In neighboring Donetsk region, fierce fighting continued as well with several missiles striking Donetsk city late on June 4.

In Ukraine's southern Odesa region, a missile hit an agricultural storage unit, wounding two people in the morning on June 4, the regional administration's spokesman wrote on Telegram.

Ukraine announced on June 4 that four foreigners fighting for Kyiv had been killed in battle.

Russia has stepped up its offensive to take further ground in areas where Moscow-backed separatists already have a foothold as Western nations rush to get weapons to Ukraine, which lacks the firepower of Russia.

The United States earlier this week approved another $700 million in military aid for Ukraine, including four powerful rocket systems that can destroy heavy artillery as far away as 70 kilometers.

Ukraine said on June 4 that self-propelled Norwegian howitzers have now been deployed to the front lines.

In an interview with state media on June 4, Russian President Vladimir Putin claimed that his army has been "cracking" Western armaments like "nuts."

Dmitry Medvedev, the deputy chairman of Russia's Security Council and one of Putin's closest allies, warned the same day that Moscow could target western cities if Ukraine uses rocket systems supplied by the United States to carry out strikes on Russian territory.

The Biden administration said June 1 that it received assurances from Ukraine that it would not use the new U.S. rocket systems to target Russian territory. The administration said it could send additional rocket systems as needed.

U.S. Defense Secretary Lloyd Austin said on June 4 that Western countries will discuss further aid to Ukraine at a meeting in Brussels on June 15.

Britain's Defense Ministry said in its regular updates that Russian air activity remains high over Ukraine's Donbas region, with Russian aircraft conducting strikes using both guided and unguided munitions.

The ministry said on June 4 that Russia increased its use of tactical air to support its creeping advance, combining air strikes and massed artillery attacks to bring its firepower to bear as its operational focus has switched to the Donbas.

"The increased use of unguided munitions has led to the widespread destruction of built-up areas in the Donbas and has almost certainly caused substantial collateral damage and civilian casualties," it said.

But the bulletin cautioned that Russia's recent tactical successes have come at a significant cost in terms of resources, and that trend will likely continue.

Ukraine will soon receive additional anti-aircraft weapons systems from the West to help it combat Russia's dominance of the skies, a key factor in its recent gains. Germany earlier this week promised to send air-defense systems in the coming weeks.

Tens of thousands have been killed in Ukraine, more than 14 million have fled their homes, and the global economy has been disrupted by Russia’s unprovoked war, which marked its 100th day on June 3.

With reporting by Reuters, Kyiv Independent, and dpa