Ukrainian President Volodymyr Zelenskyy said his forces and those from Russia are fighting for “literally every meter” in the eastern city of Sievierodonetsk, while pleading to international partners that Ukraine “needs modern missile defense systems.”

In his latest nightly video message, Zelenskyy said Russia’s “key tactical goal” has not changed, with Russian forces also pushing toward Lysychansk, Bakhmut, Slovyansk, to the west and southwest of Sievierodonetsk.

With losses on both sides difficult to confirm, Zelenskyy said Russian casualties could exceed 40,000 in June.

“The Russian army is trying to deploy reserve forces in Donbas,” he said. “But what reserves can they have now? It seems that they will try to throw into battle poorly trained conscripts and those who were gathered by covert mobilization. Russian generals see their people simply as the cannon fodder they need to gain an advantage in numbers — in manpower, in military equipment.”

Britain’s defense ministry said Monday that in recent days the battle around Sievierodonetsk “has continued to rage.”

The ministry said Russia’s ability to carry out river crossing operations will likely be one of the most important factors in the war in the coming months.

“To achieve success in the current operational phase of its Donbas offensive, Russia is either going to have to complete ambitious flanking actions, or conduct assault river crossings,” it said.

Russian forces bombarded a chemical plant sheltering hundreds of soldiers and civilians in Sievierodonetsk on Sunday, but the Luhansk regional governor said the plant remained under Ukrainian control.

Russia claims it already controls 97% of the Luhansk province. But capturing the industrial city of Sievierodonetsk, with a prewar population of 100,000, remains crucial to Moscow’s broader goal of controlling the eastern Donbas region, which encompasses the Luhansk and Donetsk provinces.

Russia seized Ukraine’s Crimean Peninsula in 2014 and Kyiv’s forces have been fighting pro-Russian separatists in the Donbas region since then.

Leonid Pasechnik, the head of the separatist-declared Luhansk People’s Republic, acknowledged, “Sievierodonetsk is not completely 100% liberated. So, it’s impossible to call the situation calm in Sievierodonetsk, that it is completely ours.”

A Ukrainian serviceman walks past a gypsum manufacturing plant destroyed in a Russian bombing in Bakhmut, eastern Ukraine, May 28, 2022.

A Ukrainian serviceman walks past a gypsum manufacturing plant destroyed in a Russian bombing in Bakhmut, eastern Ukraine, May 28, 2022.

Some material in this report came from Reuters and The Associated Press.