Ukraine failed to safely evacuate all of its troops from the eastern city of Avdiivka during its disorderly withdrawal last weekend. At least six wounded soldiers from the 110th Brigade were stuck behind Russian lines, where they were apparently later "executed," the brigade said in a statement.

Military officials who took part in the operation said they did not know how many other soldiers were also left behind. Any number of casualties will further deteriorate morale on the front lines as Ukrainian troops, already outgunned and outnumbered, struggle to replenish their ranks.