As the conflict entered its fourth month, President Volodymyr Zelenskiy warned in his nightly address on May 24 that the coming period of time will be "extremely difficult," especially in the eastern Donbas region.

"All the power of the Russian Army, which still remains in them, has been thrown into the attack,” Zelenskiy said.

The Russian forces are aiming to destroy everything in Lyman, Popasna, Severodonetsk, and Slovyansk, he said.

"But in the interceptions of their conversations, we hear that they are well aware that this war does not make sense for Russia and that strategically their army has no chance,” he said.

It will take time and “a lot of extraordinary efforts” for Ukrainians to break their advantage in equipment and weapons, Zelenskiy said, as he again called for Western countries to supply more heavy weapons.

Providing rocket-propelled grenades, tanks, anti-ship, and other weapons to Ukraine is the best investment to maintain stability in the world and prevent many "Severe crises" that he said Russia is still planning.

Zelenskiy spoke earlier on May 24 to the World Economic Forum in Davos, Switzerland, saying that Russia had carried out nearly 1,500 missile strikes and over 3,000 air strikes against Ukraine in the first three months of the war.

British intelligence said in its daily report on May 24 that Russians are seeking to encircle Severodonetsk, a city of some 100,000 people, but are also focusing their attacks on Lysychansk and Rubyzhne in the same area.

The report said that Russian forces had achieved some localized successes in the area with the aid of intense artillery fire, but Ukrainian resistance is strong and Kyiv's Joint Force Operation command structure has remained in control of this segment of the front.

Russia's capture of Severodonetsk would see the whole of the Luhansk region falling under Russian occupation, the report said.

Amid the fighting, two top Russian officials appeared to acknowledge that Moscow’s advance has been slower than expected, though they vowed the offensive would achieve its goals.

Nikolai Patrushev, secretary of Russia’s Security Council, said the Russian government “is not chasing deadlines.”

Defense Minister Sergei Shoigu told a meeting of a Russia-led security alliance of former Soviet states that Moscow is deliberately slowing down its offensive to allow residents of encircled cities to evacuate.

Russian officials also announced that Moscow’s forces had finished clearing mines from the waters off Mariupol and that a safe corridor will open on May 25 for the exit of as many as 70 foreign ships from Ukraine’s southern coast.

With Russia's military campaign now in its most active phase, a Ukrainian Defense Ministry spokesman said battles being fought in eastern Ukraine could determine the country's fate.

In the Donetsk region, Moscow’s troops took over the industrial town of Svitlodarsk, home to a thermal power station, and raised the Russian flag there, Serhiy Goshko, head of the local Ukrainian military administration, told Ukraine’s Vilny Radio.

The governor of Luhansk, Serhiy Hayday, said that the Russian military was advancing in all directions at once in the region. The Russians beefed up their forces with some 12,500 soldiers who were attempting to seize Luhansk, he said.

“They brought over an insane number of fighters and equipment," Hayday said on Telegram. “The invaders are killing our cities, destroying everything around.” He added that Luhansk is becoming “like Mariupol.”

Mariupol was relentlessly pounded during a nearly three-month siege that ended last week after some 2,500 Ukrainian fighters abandoned a steel plant where they had made their last stand.

Workers digging through the rubble of an apartment building in Mariupol found 200 decomposing bodies in the basement, Ukrainian authorities said on May 24.

Petro Andryushchenko, an adviser to the mayor, did not say when they were discovered, but the number of victims makes it one of the deadliest known attacks of the war.

If the Russians are successful and the Donbas front line moves further west, British intelligence estimated that Russian lines of communication would be overstretched and likely lead to further logistic resupply difficulties.