Russian troops are intensifying their offensive in Severodonetsk. The city is seen as Ukraine's last stronghold in the eastern region of Luhansk.

Ukrainian President Volodymyr Zelenskyy on Sunday expressed his country's resolve to mount counterattacks against Russia on all fronts with military assistance from Western nations.

Against this backdrop, Russian Foreign Minister Sergey Lavrov claimed that the "liberation" of the Donetsk and Luhansk regions is an unconditional priority for Russia.

He made the comment in an interview with a French TV channel on Sunday.

Meanwhile, Britain's defense ministry intelligence update on Sunday said the Russian army has likely suffered devastating losses among its mid-ranking and junior officials.

It also took note of multiple credible reports of localized mutinies among Russia's forces in Ukraine.

On Monday, Russian President Vladimir Putin is expected to speak by phone with Turkish President Recep Tayyip Erdogan.

Attention is focused on Turkey now, as the country is set to play a role in deciding whether Finland and Sweden will be accepted as members of the North Atlantic Treaty Organization. Putin appears to want to keep NATO's expansion in check.

Erdogan, meanwhile, appears ready to hold phone talks with Zelenskyy in a likely bid to resume stalled ceasefire talks between Russia and Ukraine.