The timing of Russia’s advance is a calamity for Kyiv, which already fears its most important ally will abandon it as Trump floats exchanging territories to end the war.

"What has been building up for the Ukrainians is fundamentally a manpower issue," a former senior Pentagon adviser told Newsweek.

President Trump has abandoned a push for a cease-fire, arguing instead for a full peace agreement, a position held by Russian President Vladimir Putin.

Russia's advance in the east has resulted in Ukraine shifting some of its most experienced troops there in an attempt to blunt it.

Russian forces have moved several miles into Ukrainian-held territory in the east, threatening to outflank Ukraine’s positions.

US President Donald Trump and Russia’s Vladimir Putin met Friday for a summit in Alaska aimed - on the US side at least - at bringing an end to the grinding war that has followed Russia’s full-scale invasion of 2022.

Ukraine is facing its worst manpower crisis since the start of the war with Russia, with The Telegraph reporting that at least 650,000 fighting-age men have fled the country since 2022. Many others are hiding within Ukraine or bribing officials to avoid conscription.

The General Staff said more than 110,000 Russian troops are concentrated in the Pokrovsk area and are attempting to penetrate defenses by sending small infantry units between Ukrainian lines.